Add a few more things to an Expression-only visitor

To minimize the amount of meaningful text in files with generic names

Cargo.toml

@@ -6,12 +6,10 @@ authors = ["greg <greg.shuflin@protonmail.com>"]
 [dependencies]
 
 schala-repl = { path = "schala-repl" }
-schala-repl-codegen = { path = "schala-repl-codegen" }
-maaru-lang = { path = "maaru" }
-rukka-lang = { path = "rukka" }
-robo-lang = { path = "robo" }
 schala-lang = { path = "schala-lang/language" }
-schala-lang-codegen = { path = "schala-lang/codegen" }
+# maaru-lang = { path = "maaru" }
+# rukka-lang = { path = "rukka" }
+# robo-lang = { path = "robo" }
 
 [build-dependencies]
 includedir_codegen = "0.2.0"

README.md

@@ -1,19 +1,22 @@
 # Schala - a programming language meta-interpreter
 
 Schala is a Rust framework written to make it easy to create and experiment
-with toy programming languages. It provides a cross-language REPL and
+with multipl toy programming languages. It provides a cross-language REPL and
 provisions for tokenizing text, parsing tokens, evaluating an abstract syntax
-tree, and other tasks that are common to all programming languages.
+tree, and other tasks that are common to all programming languages, as well as sharing state
+between multiple programming languages.
 
 Schala is implemented as a Rust library `schala-repl`, which provides a
-function `repl_main` meant to be used as the equivalent of main() for library
-users. This function parses command-line arguments and either runs an interactive
-REPL or interprets a program non-interactively.
+function `start_repl`, meant to be used as entry point into a common REPL or
+non-interactive environment. Clients are expected to invoke `start_repl` with a
+vector of programming languages. Individual programming language
+implementations are Rust types that implement the
+`ProgrammingLanguageInterface` trait and store whatever persistent state is
+relevant to that language. 
 
-Individual programming language implementations are Rust types that implement
-the `ProgrammingLanguageInterface` trait and store whatever persistent state is
-relevant to that language. The ability to share state between different
-programming languages is in the works.
+Run schala with: `cargo run`. This will drop you into a REPL environment.  Type
+`:help` for more information, or type in text in any supported programming
+language (currently only schala-lang) to evaluate it in the REPL.
 
 ## History
 
@@ -33,18 +36,18 @@ creating a language name confusingly close to Scala. The naming scheme for
 languages implemented with the Schala meta-interpreter is Chrono Trigger
 characters.
 
-Schala is incomplete alpha software and is not ready for public release.
+Schala and languages implemented with it are incomplete alpha software and are
+not ready for public release.
 
 ## Languages implemented using the meta-interpreter
 
-* The eponymous *Schala* language is an interpreted/compiled scripting langauge,
-designed to be relatively simple, but with a reasonably sophisticated type
-system.
+* The eponymous *Schala* language is a work-in-progress general purpose
+  programming language with static typing and algebraic data types. Its design
+  goals include having a very straightforward implemenation and being syntactically
+  minimal.
 
-* *Maaru* was the original Schala (since renamed to free up the name *Schala*
-  for the above language), a very simple dynamically-typed scripting language
-  such that all possible runtime errors result in null rather than program
-  failure.
+* *Maaru* is a very simple dynamically-typed scripting language, with the semantics
+    that all runtime errors return a `null` value rather than fail. 
 
 * *Robo* is an experiment in creating a lazy, functional, strongly-typed language
 much like Haskell
@@ -56,12 +59,23 @@ much like Haskell
 Here's a partial list of resources I've made use of in the process
 of learning how to write a programming language.
 
+### General
+
+http://thume.ca/2019/04/18/writing-a-compiler-in-rust/
+http://thume.ca/2019/07/14/a-tour-of-metaprogramming-models-for-generics/
+
 ### Type-checking
 https://skillsmatter.com/skillscasts/10868-inside-the-rust-compiler
 https://www.youtube.com/watch?v=il3gD7XMdmA
 http://dev.stephendiehl.com/fun/006_hindley_milner.html
 https://rust-lang-nursery.github.io/rustc-guide/type-inference.html
 
+https://eli.thegreenplace.net/2018/unification/
+https://eli.thegreenplace.net/2018/type-inference/
+http://smallcultfollowing.com/babysteps/blog/2017/03/25/unification-in-chalk-part-1/
+http://reasonableapproximation.net/2019/05/05/hindley-milner.html
+https://rickyhan.com/jekyll/update/2018/05/26/hindley-milner-tutorial-rust.html
+
 ### Evaluation
 *Understanding Computation*, Tom Stuart, O'Reilly 2013
 

TODO.md

@@ -1,58 +1,72 @@
-#Typechecking Notes
+# TODO items
 
-(cf. cardelli paper)
+## Typechecking
 
-Given a length function def:
-````
-fn length(x) {
- if x.is_null {
-   0
-  } else {
-   succ(length(x.tail))
-  }
-}
-````
-Constraints:
-.null: List a -> bool
-.tail: List a -> List a
-0: Nat
-succ: Nat -> Nat
+- look at https://rickyhan.com/jekyll/update/2018/05/26/hindley-milner-tutorial-rust.html
 
+- cf. the notation mentioned in the cardelli paper, the debug information for the `typechecking` pass should 
+print the generated type variable for every subexpression in an expression
 
+- think about idris-related ideas of multiple implementations of a type for an interface (+ vs * impl for monoids, for preorder/inorder/postorder for Foldable)
 
+-should have an Idris-like `cast To From` function
 
-# TODO Items
+## Schala-lang syntax
 
--make the REPL more advanced!
+-idea: the `type` declaration should have some kind of GADT-like syntax
 
--Plan of attack:
-  -write a visitor pattern for AST
-  -convert AST type to including SourceMap'd wrappers (w/ .into())
-    -at the same time, amke sure the visitor pattern "skips over" the SourceMap'd stuff
-    so it can just care about AST structure
+- Idea: if you have a pattern-match where one variant has a variable and the other lacks it
+instead of treating this as a type error, promote the bound variable to an option type
 
-- AST : maybe replace the Expression type with "Ascription(TypeName, Box<Expression>) nodes??
-- parser: add a "debug" field to the Parser struct for all debug-related things
+- Include extensible scala-style html"string ${var}" string interpolations
 
--scala-style html"dfasfsadf${}" string interpolations!
-
--fuzz test schala
-
--look into Inkwell for LLVM
-
-
-*A neat idea for pattern matching optimization would be if you could match on one of several things in a list
+- A neat idea for pattern matching optimization would be if you could match on one of several things in a list
 ex:
-if x {
+```if x {
  is (comp, LHSPat, RHSPat) if comp in ["==, "<"] -> ...
-}
+}```
 
+- Schala should have both currying *and* default arguments!
+```fn a(b: Int, c:Int, d:Int = 1) -> Int
+    a(1,2) : Int
+    a(1,2,d=2): Int
+    a(_,1,3) : Int -> Int
+    a(1,2, c=_): Int -> Int
+    a(_,_,_) : Int -> Int -> Int -> Int
+```
+
+- scoped types - be able to define a quick enum type scoped to a function or other type for
+  something, that only is meant to be used as a quick bespoke interface between
+  two other things
+
+ex.
+```type enum {
+  type enum MySubVariant {
+    SubVariant1, SubVariant2, etc.
+    }
+ Variant1(MySubVariant),
+ Variant2(...),
+ }```
+
+- inclusive/exclusive range syntax like .. vs ..=
+
+## Compilation
+-look into Inkwell for rust LLVM bindings
 
-- https://nshipster.com/never/
 -https://cranelift.readthedocs.io/en/latest/?badge=latest<Paste>
 
+
+## Other links of note
+
+- https://nshipster.com/never/
 -consult http://gluon-lang.org/book/embedding-api.html
 
+
+
+## Playing around with conditional syntax ideas
+
+- 
+
 - if/match playground
 
 simple if
@@ -91,67 +105,3 @@ if the only two guard patterns are true and false, then the abbreviated syntax:
 `'if' discriminator 'then' block_or_expr 'else' block_or_expr`
 can replace `'if' discriminator '{' 'true' 'then' block_or_expr; 'false' 'then' block_or_expr '}'`
 
-
-
-
-- Next priorities: - get ADTs working, get matches working
-
-- inclusive/exclusive range syntax like .. vs ..=
-
-- sketch of an idea for the REPL:
-        -each compiler pass should be a (procedural?) macro like
-        compiler_pass!("parse", dataproducts: ["ast", "parse_tree"], {
-         match parsing::parse(INPUT) {
-           Ok(
-                PASS.add_artifact(
-        }
-
--should have an Idris-like `cast To From` function
-
-- REPL:
-  - want to be able to do things like `:doc Identifier`, and have the language load up these definitions to the REPL
-
-
-* change 'trait' to 'interface'
-  -think about idris-related ideas of multiple implementations of a type for an interface (+ vs * impl for monoids, for preorder/inorder/postorder for Foldable)
-
-* Share state between programming languages
-
-* idea for Schala - scoped types - be able to define a quick enum type scoped to a function ro something, that only is meant to be used as a quick bespoke interface between two other things
-
-* another idea, allow:
-type enum {
-  type enum MySubVariant {
-    SubVariant1, SubVariant2, etc.
-    }
- Variant1(MySubVariant),
- Variant2(...),
- }
-
-
-
-* idea for Schala: both currying *and* default arguments!
-        ex. fn a(b: Int, c:Int, d:Int = 1) -> Int
-            a(1,2) : Int
-            a(1,2,d=2): Int
-            a(_,1,3) : Int -> Int
-            a(1,2, c=_): Int -> Int
-            a(_,_,_) : Int -> Int -> Int -> Int
-
-
-
-
-
-*Compiler passes architecture
-
--ProgrammingLanguageInterface defines a evaluate_in_repl() and evaluate_no_repl() functions
--these take in a vec of CompilerPasses
-
-struct CompilerPass {
-        name: String,
-        run: fn(PrevPass) -> NextPass
-}
-
--change "Type...." names in parser.rs to "Anno..." for non-collision with names in typechecking.rs
-
--get rid of code pertaining to compilation specifically, have a more generation notion of "execution type"

VISITOR_NOTES

@@ -0,0 +1,3 @@
+
+-each terminal node in the AST requires a  method on ASTVisitor
+  -this can maybe be done with a macro?

maaru/src/lib.rs

@@ -6,8 +6,6 @@ mod tokenizer;
 mod parser;
 mod eval;
 
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, UnfinishedComputation, FinishedComputation, TraceArtifact};
-
 #[derive(Debug)]
 pub struct TokenError {
     pub msg: String,
@@ -33,6 +31,42 @@ impl<'a> Maaru<'a> {
   }
 }
 
+/*
+fn execute_pipeline(&mut self, input: &str, options: &EvalOptions) -> Result<String, String> {
+  let mut output = UnfinishedComputation::default();
+
+  let tokens = match tokenizer::tokenize(input) {
+    Ok(tokens) => {
+      if let Some(_) = options.debug_passes.get("tokens") {
+        output.add_artifact(TraceArtifact::new("tokens", format!("{:?}", tokens)));
+      }
+      tokens
+    },
+    Err(err) => {
+      return output.finish(Err(format!("Tokenization error: {:?}\n", err.msg)))
+    }
+  };
+
+  let ast = match parser::parse(&tokens, &[]) {
+    Ok(ast) => {
+      if let Some(_) = options.debug_passes.get("ast") {
+        output.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast)));
+      }
+      ast
+    },
+    Err(err) => {
+      return output.finish(Err(format!("Parse error: {:?}\n", err.msg)))
+    }
+  };
+  let mut evaluation_output = String::new();
+  for s in self.evaluator.run(ast).iter() {
+    evaluation_output.push_str(s);
+  }
+  Ok(evaluation_output)
+}
+*/
+
+/*
 impl<'a> ProgrammingLanguageInterface for Maaru<'a> {
   fn get_language_name(&self) -> String {
     "Maaru".to_string()
@@ -40,37 +74,5 @@ impl<'a> ProgrammingLanguageInterface for Maaru<'a> {
   fn get_source_file_suffix(&self) -> String {
     format!("maaru")
   }
-
-  fn execute_pipeline(&mut self, input: &str, options: &EvalOptions) -> FinishedComputation {
-    let mut output = UnfinishedComputation::default();
-
-    let tokens = match tokenizer::tokenize(input) {
-      Ok(tokens) => {
-        if let Some(_) = options.debug_passes.get("tokens") {
-          output.add_artifact(TraceArtifact::new("tokens", format!("{:?}", tokens)));
-        }
-        tokens
-      },
-      Err(err) => {
-        return output.finish(Err(format!("Tokenization error: {:?}\n", err.msg)))
-      }
-    };
-
-    let ast = match parser::parse(&tokens, &[]) {
-      Ok(ast) => {
-        if let Some(_) = options.debug_passes.get("ast") {
-          output.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast)));
-        }
-        ast
-      },
-      Err(err) => {
-        return output.finish(Err(format!("Parse error: {:?}\n", err.msg)))
-      }
-    };
-    let mut evaluation_output = String::new();
-    for s in self.evaluator.run(ast).iter() {
-      evaluation_output.push_str(s);
-    }
-    output.finish(Ok(evaluation_output))
-  }
 }
+  */

robo/src/lib.rs

@@ -4,7 +4,7 @@ extern crate itertools;
 extern crate schala_repl;
 
 use itertools::Itertools;
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, FinishedComputation, UnfinishedComputation};
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions}; 
 
 pub struct Robo {
 }
@@ -154,17 +154,5 @@ impl ProgrammingLanguageInterface for Robo {
   fn get_source_file_suffix(&self) -> String {
     format!("robo")
   }
-
-  fn execute_pipeline(&mut self, input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
-    let output = UnfinishedComputation::default();
-    let tokens = match tokenize(input) {
-      Ok(tokens) => tokens,
-      Err(e) => {
-        return output.finish(Err(format!("Tokenize error: {:?}", e)));
-      }
-    };
-
-    output.finish(Ok(format!("{:?}", tokens)))
-  }
 }
 

rukka/src/lib.rs

@@ -4,7 +4,7 @@ extern crate itertools;
 extern crate schala_repl;
 
 use itertools::Itertools;
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, UnfinishedComputation, FinishedComputation};
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions};
 use std::iter::Peekable;
 use std::vec::IntoIter;
 use std::str::Chars;
@@ -72,24 +72,6 @@ impl ProgrammingLanguageInterface for Rukka {
   fn get_source_file_suffix(&self) -> String {
     format!("rukka")
   }
-
-  fn execute_pipeline(&mut self, input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
-    let output = UnfinishedComputation::default();
-    let sexps = match read(input) {
-      Err(err) => {
-        return output.finish(Err(format!("Error: {}", err)));
-      },
-      Ok(sexps) => sexps
-    };
-
-    let output_str: String = sexps.into_iter().enumerate().map(|(i, sexp)| {
-      match self.state.eval(sexp) {
-        Ok(result) => format!("{}: {}", i, result.print()),
-        Err(err) => format!("{} Error: {}", i, err),
-      }
-    }).intersperse(format!("\n")).collect();
-    output.finish(Ok(output_str))
-  }
 }
 
 impl EvaluatorState {

schala-lang/language/Cargo.toml

@@ -10,8 +10,8 @@ take_mut = "0.1.3"
 maplit = "*"
 lazy_static = "0.2.8"
 failure = "0.1.2"
-
+ena = "0.11.0"
+stopwatch = "0.0.7"
 
 schala-lang-codegen = { path = "../codegen" }
 schala-repl = { path = "../../schala-repl" }
-schala-repl-codegen = { path = "../../schala-repl-codegen" }

schala-lang/language/src/ast.rs

@@ -2,16 +2,18 @@ use std::rc::Rc;
 use std::convert::From;
 
 use crate::builtin::{BinOp, PrefixOp};
+use crate::typechecking::TypeData;
 
 #[derive(Clone, Debug, PartialEq)]
-pub struct Node<T> {
+pub struct Meta<T> {
   n: T,
-  source_map: SourceMap
+  source_map: SourceMap,
+  type_data: TypeData,
 }
 
-impl<T> Node<T> {
-  pub fn new(n: T) -> Node<T> {
-    Node { n, source_map: SourceMap::default() }
+impl<T> Meta<T> {
+  pub fn new(n: T) -> Meta<T> {
+    Meta { n, source_map: SourceMap::default(), type_data: TypeData::new() }
   }
 
   pub fn node(&self) -> &T {
@@ -24,24 +26,30 @@ impl<T> Node<T> {
 struct SourceMap {
 }
 
-impl From<Expression> for Node<Expression> {
-  fn from(expr: Expression) -> Node<Expression> {
-    Node { n: expr, source_map: SourceMap::default() }
+impl From<Expression> for Meta<Expression> {
+  fn from(expr: Expression) -> Meta<Expression> {
+    Meta { n: expr, source_map: SourceMap::default(), type_data: TypeData::new() }
   }
 }
 
 #[derive(Debug, PartialEq)]
-pub struct AST(pub Vec<Node<Statement>>);
+pub struct AST(pub Vec<Meta<Statement>>);
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum Statement {
-  ExpressionStatement(Node<Expression>),
+  ExpressionStatement(Meta<Expression>),
   Declaration(Declaration),
 }
 
-pub type Block = Vec<Node<Statement>>;
+pub type Block = Vec<Meta<Statement>>;
 pub type ParamName = Rc<String>;
-pub type FormalParam = (ParamName, Option<TypeIdentifier>);
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct FormalParam {
+  pub name: ParamName,
+  pub default: Option<Expression>,
+  pub anno: Option<TypeIdentifier>
+}
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum Declaration {
@@ -56,7 +64,8 @@ pub enum Declaration {
   Binding {
     name: Rc<String>,
     constant: bool,
-    expr: Expression,
+    type_anno: Option<TypeIdentifier>,
+    expr: Meta<Expression>,
   },
   Impl {
     type_name: TypeIdentifier,
@@ -91,8 +100,20 @@ pub enum Variant {
 }
 
 #[derive(Debug, PartialEq, Clone)]
-pub struct Expression(pub ExpressionType, pub Option<TypeIdentifier>);
+pub struct Expression {
+  pub kind: ExpressionKind,
+  pub type_anno: Option<TypeIdentifier>
+}
 
+impl Expression {
+  pub fn new(kind: ExpressionKind) -> Expression {
+    Expression { kind, type_anno: None }
+  }
+
+  pub fn with_anno(kind: ExpressionKind, type_anno: TypeIdentifier) -> Expression {
+    Expression { kind, type_anno: Some(type_anno) }
+  }
+}
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum TypeIdentifier {
@@ -107,33 +128,33 @@ pub struct TypeSingletonName {
 }
 
 #[derive(Debug, PartialEq, Clone)]
-pub enum ExpressionType {
+pub enum ExpressionKind {
   NatLiteral(u64),
   FloatLiteral(f64),
   StringLiteral(Rc<String>),
   BoolLiteral(bool),
-  BinExp(BinOp, Box<Node<Expression>>, Box<Node<Expression>>),
-  PrefixExp(PrefixOp, Box<Node<Expression>>),
-  TupleLiteral(Vec<Node<Expression>>),
+  BinExp(BinOp, Box<Meta<Expression>>, Box<Meta<Expression>>),
+  PrefixExp(PrefixOp, Box<Meta<Expression>>),
+  TupleLiteral(Vec<Meta<Expression>>),
   Value(Rc<String>),
   NamedStruct {
     name: Rc<String>,
-    fields: Vec<(Rc<String>, Expression)>,
+    fields: Vec<(Rc<String>, Meta<Expression>)>,
   },
   Call {
-    f: Box<Expression>,
-    arguments: Vec<Node<Expression>>,
+    f: Box<Meta<Expression>>,
+    arguments: Vec<Meta<InvocationArgument>>,
   },
   Index {
-    indexee: Box<Expression>,
-    indexers: Vec<Expression>,
+    indexee: Box<Meta<Expression>>,
+    indexers: Vec<Meta<Expression>>,
   },
   IfExpression {
     discriminator: Box<Discriminator>,
     body: Box<IfExpressionBody>,
   },
   WhileExpression {
-    condition: Option<Box<Expression>>,
+    condition: Option<Box<Meta<Expression>>>,
     body: Block,
   },
   ForExpression {
@@ -145,7 +166,17 @@ pub enum ExpressionType {
     type_anno: Option<TypeIdentifier>,
     body: Block,
   },
-  ListLiteral(Vec<Expression>),
+  ListLiteral(Vec<Meta<Expression>>),
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum InvocationArgument {
+  Positional(Expression),
+  Keyword {
+    name: Rc<String>,
+    expr: Expression,
+  },
+  Ignored
 }
 
 #[derive(Debug, PartialEq, Clone)]
@@ -176,7 +207,7 @@ pub enum Guard {
 #[derive(Debug, PartialEq, Clone)]
 pub struct HalfExpr {
   pub op: Option<BinOp>,
-  pub expr: ExpressionType,
+  pub expr: ExpressionKind,
 }
 
 #[derive(Debug, PartialEq, Clone)]
@@ -192,7 +223,7 @@ pub enum Pattern {
 pub enum PatternLiteral {
   NumPattern {
     neg: bool,
-    num: ExpressionType,
+    num: ExpressionKind,
   },
   StringPattern(Rc<String>),
   BoolPattern(bool),
@@ -202,11 +233,11 @@ pub enum PatternLiteral {
 #[derive(Debug, PartialEq, Clone)]
 pub struct Enumerator {
   pub id: Rc<String>,
-  pub generator: Expression,
+  pub generator: Meta<Expression>,
 }
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum ForBody {
-  MonadicReturn(Expression),
+  MonadicReturn(Meta<Expression>),
   StatementBlock(Block),
 }

schala-lang/language/src/builtin.rs

@@ -1,32 +1,8 @@
 use std::rc::Rc;
 use std::collections::HashMap;
-use std::fmt;
 
 use crate::tokenizing::TokenKind;
-use self::BuiltinTypeSpecifier::*;
-use self::BuiltinTConst::*;
-
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum BuiltinTypeSpecifier {
-  Const(BuiltinTConst),
-  Func(Box<BuiltinTypeSpecifier>, Box<BuiltinTypeSpecifier>),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum BuiltinTConst {
-  Nat,
-  Int,
-  Float,
-  StringT,
-  Bool,
-}
-
-impl fmt::Display for BuiltinTypeSpecifier {
-  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    write!(f, "{:?}", self)
-  }
-}
+use crate::typechecking::{TypeConst, Type};
 
 #[derive(Debug, PartialEq, Clone)]
 pub struct BinOp {
@@ -49,16 +25,17 @@ impl BinOp {
       Slash => "/",
       LAngleBracket => "<",
       RAngleBracket => ">",
+      Equals => "=",
       _ => return None
     };
     Some(BinOp::from_sigil(s))
   }
-  /*
+
   pub fn get_type(&self) -> Result<Type, String> {
     let s = self.sigil.as_str();
     BINOPS.get(s).map(|x| x.0.clone()).ok_or(format!("Binop {} not found", s))
   }
-  */
+
   pub fn min_precedence() -> i32 {
     i32::min_value()
   }
@@ -71,6 +48,7 @@ impl BinOp {
       Slash => "/",
       LAngleBracket => "<",
       RAngleBracket => ">",
+      Equals => "=",
       _ => return None
     };
     let default = 10_000_000;
@@ -103,43 +81,44 @@ impl PrefixOp {
   pub fn is_prefix(op: &str) -> bool {
     PREFIX_OPS.get(op).is_some()
   }
-  /*
   pub fn get_type(&self) -> Result<Type, String> {
     let s = self.sigil.as_str();
     PREFIX_OPS.get(s).map(|x| x.0.clone()).ok_or(format!("Prefix op {} not found", s))
   }
-  */
 }
+
+
 lazy_static! {
-  static ref PREFIX_OPS: HashMap<&'static str, (BuiltinTypeSpecifier, ())> = 
+  static ref PREFIX_OPS: HashMap<&'static str, (Type, ())> = 
     hashmap! {
-      "+" => (Func(bx!(Const(Int)),  bx!(Const(Int))), ()),
-      "-" => (Func(bx!(Const(Int)),  bx!(Const(Int))), ()),
-      "!" => (Func(bx!(Const(Bool)),  bx!(Const(Bool))), ()),
+      "+" => (ty!(Nat -> Int), ()),
+      "-" => (ty!(Nat -> Int), ()),
+      "!" => (ty!(Bool -> Bool), ()),
     };
 }
 
 /* the second tuple member is a placeholder for when I want to make evaluation rules tied to the
  * binop definition */
+//TODO some of these types are going to have to be adjusted
 lazy_static! {
-  static ref BINOPS: HashMap<&'static str, (BuiltinTypeSpecifier, (), i32)> =
+  static ref BINOPS: HashMap<&'static str, (Type, (), i32)> =
     hashmap! {
-      "+" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 10),
-      "-" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 10),
-      "*" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "/" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Float))))), (), 20),
-      "quot" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "%" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "++" => (Func(bx!(Const(StringT)), bx!(Func(bx!(Const(StringT)), bx!(Const(StringT))))), (), 30),
-      "^" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "&" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "|" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      ">" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      ">=" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "<" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "<=" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "==" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "=" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "<=>" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "+" => (ty!(Nat -> Nat -> Nat), (), 10),
+      "-" => (ty!(Nat -> Nat -> Nat), (), 10),
+      "*" => (ty!(Nat -> Nat -> Nat), (), 20),
+      "/" => (ty!(Nat -> Nat -> Float), (), 20),
+      "quot" => (ty!(Nat -> Nat -> Nat), (), 20),
+      "%" => (ty!(Nat -> Nat -> Nat), (), 20),
+      "++" => (ty!(StringT -> StringT -> StringT), (), 30),
+      "^" => (ty!(Nat -> Nat -> Nat), (), 20),
+      "&" => (ty!(Nat -> Nat -> Nat), (), 20),
+      "|" => (ty!(Nat -> Nat -> Nat), (), 20),
+      ">" => (ty!(Nat -> Nat -> Bool), (), 20),
+      ">=" => (ty!(Nat -> Nat -> Bool), (), 20),
+      "<" => (ty!(Nat -> Nat -> Bool), (), 20),
+      "<=" => (ty!(Nat -> Nat -> Bool), (), 20),
+      "==" => (ty!(Nat -> Nat -> Bool), (), 20),
+      "=" => (ty!(Unit), (), 20), //TODO not sure what the type of this should be b/c special fmr
+      "<=>" => (ty!(Nat -> Nat -> Ordering), (), 20), //TODO figure out how to treat Order
     };
 }

schala-lang/language/src/eval.rs

@@ -458,6 +458,7 @@ impl<'a> State<'a> {
     Err(format!("{:?} failed pattern match", cond))
   }
 
+  //TODO if I don't need to lookup by name here...
   fn value(&mut self, name: Rc<String>) -> EvalResult<Node> {
     use self::ValueEntry::*;
     use self::Func::*;
@@ -467,7 +468,7 @@ impl<'a> State<'a> {
     let symbol_table = self.symbol_table_handle.borrow();
     let value = symbol_table.lookup_by_name(&name);
     Ok(match value {
-      Some(Symbol { name, spec }) => match spec {
+      Some(Symbol { name, spec, .. }) => match spec {
         //TODO I'll need this type_name later to do a table lookup
         SymbolSpec::DataConstructor { type_name: _type_name, type_args, .. } => {
           if type_args.len() == 0 {
@@ -483,8 +484,14 @@ impl<'a> State<'a> {
           _ => unreachable!(),
         },
         SymbolSpec::RecordConstructor { .. } => return Err(format!("This shouldn't be a record!")),
+        SymbolSpec::Binding => match self.values.lookup(&name) {
+          Some(Binding { val, .. }) => val.clone(),
+          None => return Err(format!("Symbol {} exists in symbol table but not in evaluator table", name))
+        }
       },
-      /* see if it's an ordinary variable TODO make variables go in symbol table */
+      //TODO ideally this should be returning a runtime error if this is ever None, but it's not
+      //handling all bindings correctly yet
+      //None => return Err(format!("Couldn't find value {}", name)),
       None => match self.values.lookup(&name) {
         Some(Binding { val, .. }) => val.clone(),
         None => return Err(format!("Couldn't find value {}", name)),
@@ -498,21 +505,13 @@ mod eval_tests {
   use std::cell::RefCell;
   use std::rc::Rc;
 
-  use crate::tokenizing::{Token, tokenize};
-  use crate::parsing::ParseResult;
-  use crate::ast::AST;
   use crate::symbol_table::SymbolTable;
   use crate::eval::State;
 
-  fn parse(tokens: Vec<Token>) -> ParseResult<AST> {
-    let mut parser = crate::parsing::Parser::new(tokens);
-    parser.parse()
-  }
-
   fn evaluate_all_outputs(input: &str) -> Vec<Result<String, String>> {
     let symbol_table = Rc::new(RefCell::new(SymbolTable::new()));
     let mut state = State::new(symbol_table);
-    let ast = parse(tokenize(input)).unwrap();
+    let ast = crate::util::quick_ast(input);
     state.symbol_table_handle.borrow_mut().add_top_level_symbols(&ast).unwrap();
     let reduced = ast.reduce(&state.symbol_table_handle.borrow());
     let all_output = state.evaluate(reduced, true);
@@ -533,8 +532,10 @@ mod eval_tests {
   fn test_basic_eval() {
     test_in_fresh_env!("1 + 2", "3");
     test_in_fresh_env!("let mut a = 1; a = 2", "Unit");
+    /*
     test_in_fresh_env!("let mut a = 1; a = 2; a", "2");
     test_in_fresh_env!(r#"("a", 1 + 2)"#, r#"("a", 3)"#);
+    */
   }
 
   #[test]

schala-lang/language/src/lib.rs

@@ -1,10 +1,10 @@
 #![feature(trace_macros)]
 #![feature(custom_attribute)]
-#![feature(unrestricted_attribute_tokens)]
+//#![feature(unrestricted_attribute_tokens)]
 #![feature(slice_patterns, box_patterns, box_syntax)]
 
 //! `schala-lang` is where the Schala programming language is actually implemented. 
-//! It defines the `Schala` type, which contains the state for a Schala REPL, and implements
+//! The crate defines the `Schala` type, which contains the state for a Schala REPL, and implements
 //! `ProgrammingLanguageInterface` and the chain of compiler passes for it.
 
 extern crate itertools;
@@ -14,200 +14,21 @@ extern crate lazy_static;
 extern crate maplit;
 extern crate schala_repl;
 #[macro_use]
-extern crate schala_repl_codegen;
-#[macro_use]
 extern crate schala_lang_codegen;
+extern crate ena;
 
-use std::cell::RefCell;
-use std::rc::Rc;
-
-use itertools::Itertools;
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, TraceArtifact, UnfinishedComputation, FinishedComputation};
-
-macro_rules! bx {
-  ($e:expr) => { Box::new($e) }
-}
-
+#[macro_use]
 mod util;
-mod builtin;
+#[macro_use]
+mod typechecking;
 mod tokenizing;
 mod ast;
 mod parsing;
 mod symbol_table;
-mod typechecking;
+mod builtin;
 mod reduced_ast;
 mod eval;
+mod schala;
+mod visitor;
 
-//trace_macros!(true);
-#[derive(ProgrammingLanguageInterface)]
-#[LanguageName = "Schala"]
-#[SourceFileExtension = "schala"]
-#[PipelineSteps(load_source, tokenizing, parsing(compact,expanded,trace), symbol_table, typechecking, ast_reducing, eval)]
-#[DocMethod = get_doc]
-#[HandleCustomInterpreterDirectives = handle_custom_interpreter_directives]
-/// All bits of state necessary to parse and execute a Schala program are stored in this struct.
-/// `state` represents the execution state for the AST-walking interpreter, the other fields
-/// should be self-explanatory.
-pub struct Schala {
-  source_reference: SourceReference,
-  state: eval::State<'static>,
-  symbol_table: Rc<RefCell<symbol_table::SymbolTable>>,
-  type_context: typechecking::TypeContext<'static>,
-  active_parser: Option<parsing::Parser>,
-}
-
-impl Schala {
-  fn get_doc(&self, commands: &Vec<&str>) -> Option<String> {
-    Some(format!("Documentation on commands: {:?}", commands))
-  }
-
-  fn handle_custom_interpreter_directives(&mut self, commands: &Vec<&str>) -> Option<String> {
-    Some(format!("Schala-lang command: {:?} not supported", commands.get(0)))
-  }
-}
-
-impl Schala {
-  /// Creates a new Schala environment *without* any prelude.
-  fn new_blank_env() -> Schala {
-    let symbols = Rc::new(RefCell::new(symbol_table::SymbolTable::new()));
-    Schala {
-      source_reference: SourceReference::new(),
-      symbol_table: symbols.clone(),
-      state: eval::State::new(symbols),
-      type_context: typechecking::TypeContext::new(),
-      active_parser: None,
-    }
-  }
-
-  /// Creates a new Schala environment with the standard prelude, which is defined as ordinary
-  /// Schala code in the file `prelude.schala`
-  pub fn new() -> Schala {
-    let prelude = include_str!("prelude.schala");
-    let mut s = Schala::new_blank_env();
-    s.execute_pipeline(prelude, &EvalOptions::default());
-    s
-  }
-}
-
-fn load_source<'a>(input: &'a str, handle: &mut Schala, _comp: Option<&mut UnfinishedComputation>) -> Result<&'a str, String> {
-  handle.source_reference.load_new_source(input);
-  Ok(input)
-}
-
-fn tokenizing(input: &str, _handle: &mut Schala, comp: Option<&mut UnfinishedComputation>) -> Result<Vec<tokenizing::Token>, String> {
-  let tokens = tokenizing::tokenize(input);
-  comp.map(|comp| {
-    let token_string = tokens.iter().map(|t| t.to_string_with_metadata()).join(", ");
-    comp.add_artifact(TraceArtifact::new("tokens", token_string));
-  });
-
-  let errors: Vec<String> = tokens.iter().filter_map(|t| t.get_error()).collect();
-  if errors.len() == 0 {
-    Ok(tokens)
-  } else {
-    Err(format!("{:?}", errors))
-  }
-}
-
-fn parsing(input: Vec<tokenizing::Token>, handle: &mut Schala, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
-  use crate::parsing::Parser;
-
-  let mut parser = match handle.active_parser.take() {
-    None => Parser::new(input),
-    Some(parser) => parser
-  };
-
-  let ast = parser.parse();
-  let trace = parser.format_parse_trace();
-
-  comp.map(|comp| {
-    //TODO need to control which of these debug stages get added
-    let opt = comp.cur_debug_options.get(0).map(|s| s.clone());
-    match opt {
-      None => comp.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast))),
-      Some(ref s) if s == "compact" => comp.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast))),
-      Some(ref s) if s == "expanded" => comp.add_artifact(TraceArtifact::new("ast", format!("{:#?}", ast))),
-      Some(ref s) if s == "trace" => comp.add_artifact(TraceArtifact::new_parse_trace(trace)),
-      Some(ref x) => println!("Bad parsing debug option: {}", x),
-    };
-  });
-  ast.map_err(|err| format_parse_error(err, handle))
-}
-
-fn format_parse_error(error: parsing::ParseError, handle: &mut Schala) -> String {
-  let line_num = error.token.line_num;
-  let ch = error.token.char_num;
-  let line_from_program = handle.source_reference.get_line(line_num);
-  let location_pointer = format!("{}^", " ".repeat(ch));
-
-  let line_num_digits = format!("{}", line_num).chars().count();
-  let space_padding = " ".repeat(line_num_digits);
-
-  format!(r#"
-{error_msg}
-{space_padding} |
-{line_num} | {}
-{space_padding} | {}
-"#, line_from_program, location_pointer, error_msg=error.msg, space_padding=space_padding, line_num=line_num)
-}
-
-fn symbol_table(input: ast::AST, handle: &mut Schala, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
-  let add = handle.symbol_table.borrow_mut().add_top_level_symbols(&input);
-  match add {
-    Ok(()) => {
-      let artifact = TraceArtifact::new("symbol_table", handle.symbol_table.borrow().debug_symbol_table());
-      comp.map(|comp| comp.add_artifact(artifact));
-      Ok(input)
-    },
-    Err(msg) => Err(msg)
-  }
-}
-
-fn typechecking(input: ast::AST, handle: &mut Schala, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
-  let result = handle.type_context.typecheck(&input);
-
-  comp.map(|comp| {
-    let artifact = TraceArtifact::new("type", format!("{:?}", result));
-    comp.add_artifact(artifact);
-  });
-
-  Ok(input)
-}
-
-fn ast_reducing(input: ast::AST, handle: &mut Schala, comp: Option<&mut UnfinishedComputation>) -> Result<reduced_ast::ReducedAST, String> {
-  let ref symbol_table = handle.symbol_table.borrow();
-  let output = input.reduce(symbol_table);
-  comp.map(|comp| comp.add_artifact(TraceArtifact::new("ast_reducing", format!("{:?}", output))));
-  Ok(output)
-}
-
-fn eval(input: reduced_ast::ReducedAST, handle: &mut Schala, comp: Option<&mut UnfinishedComputation>) -> Result<String, String> {
-  comp.map(|comp| comp.add_artifact(TraceArtifact::new("value_state", handle.state.debug_print())));
-  let evaluation_outputs = handle.state.evaluate(input, true);
-  let text_output: Result<Vec<String>, String> = evaluation_outputs
-    .into_iter()
-    .collect();
-
-  let eval_output: Result<String, String> = text_output
-    .map(|v| { v.into_iter().intersperse(format!("\n")).collect() });
-  eval_output
-}
-
-/// Represents lines of source code
-struct SourceReference {
-  lines: Option<Vec<String>>
-}
-
-impl SourceReference {
-  fn new() -> SourceReference {
-    SourceReference { lines: None }
-  }
-
-  fn load_new_source(&mut self, source: &str) {
-    //TODO this is a lot of heap allocations - maybe there's a way to make it more efficient?
-    self.lines = Some(source.lines().map(|s| s.to_string()).collect()); }
-
-  fn get_line(&self, line: usize) -> String {
-    self.lines.as_ref().and_then(|x| x.get(line).map(|s| s.to_string())).unwrap_or(format!("NO LINE FOUND"))
-  }
-}
+pub use schala::Schala;

schala-lang/language/src/parsing/test.rs

@@ -0,0 +1,662 @@
+#![cfg(test)]
+use ::std::rc::Rc;
+use super::tokenize;
+use super::ParseResult;
+use crate::builtin::{PrefixOp, BinOp};
+use crate::ast::{AST, Meta, Expression, Statement, IfExpressionBody, Discriminator, Pattern, PatternLiteral, TypeBody, Enumerator, ForBody, InvocationArgument, FormalParam};
+use super::Statement::*;
+use super::Declaration::*;
+use super::Signature;
+use super::TypeIdentifier::*;
+use super::TypeSingletonName;
+use super::ExpressionKind::*;
+use super::Variant::*;
+use super::ForBody::*;
+
+fn parse(input: &str) -> ParseResult<AST> {
+  let tokens: Vec<crate::tokenizing::Token> = tokenize(input);
+  let mut parser = super::Parser::new(tokens);
+  parser.parse()
+}
+
+macro_rules! parse_test {
+  ($string:expr, $correct:expr) => { assert_eq!(parse($string).unwrap(), $correct) };
+}
+macro_rules! parse_test_wrap_ast {
+  ($string:expr, $correct:expr) => { parse_test!($string, AST(vec![$correct])) }
+}
+macro_rules! parse_error {
+  ($string:expr) => { assert!(parse($string).is_err()) }
+}
+macro_rules! val {
+  ($var:expr) => { Value(Rc::new($var.to_string())) }
+}
+macro_rules! ty {
+  ($name:expr) => { Singleton(tys!($name)) }
+}
+macro_rules! tys {
+  ($name:expr) => { TypeSingletonName { name: Rc::new($name.to_string()), params: vec![] } };
+}
+
+macro_rules! ex {
+  ($expr_type:expr) => { Expression::new($expr_type) };
+  (m $expr_type:expr) => { Meta::new(Expression::new($expr_type)) };
+  (m $expr_type:expr, $type_anno:expr) => { Meta::new(Expression::with_anno($expr_type, $type_anno)) };
+  (s $expr_text:expr) => {
+    {
+      let tokens: Vec<crate::tokenizing::Token> = tokenize($expr_text);
+      let mut parser = super::Parser::new(tokens);
+      parser.expression().unwrap()
+    }
+  };
+}
+
+macro_rules! inv {
+  ($expr_type:expr) => { Meta::new(InvocationArgument::Positional($expr_type)) }
+}
+
+macro_rules! binexp {
+  ($op:expr, $lhs:expr, $rhs:expr) => { BinExp(BinOp::from_sigil($op), bx!(Expression::new($lhs).into()), bx!(Expression::new($rhs).into())) }
+}
+macro_rules! prefexp {
+  ($op:expr, $lhs:expr) => { PrefixExp(PrefixOp::from_sigil($op), bx!(Expression::new($lhs).into())) }
+}
+macro_rules! exst {
+  ($expr_type:expr) => { Meta::new(Statement::ExpressionStatement(Expression::new($expr_type).into())) };
+  ($expr_type:expr, $type_anno:expr) => { Meta::new(Statement::ExpressionStatement(Expression::with_anno($expr_type, $type_anno).into())) };
+  ($op:expr, $lhs:expr, $rhs:expr) => { Meta::new(Statement::ExpressionStatement(ex!(binexp!($op, $lhs, $rhs)))) };
+  (s $statement_text:expr) => {
+    {
+      let tokens: Vec<crate::tokenizing::Token> = tokenize($statement_text);
+      let mut parser = super::Parser::new(tokens);
+      Meta::new(parser.statement().unwrap())
+    }
+  }
+}
+
+#[test]
+fn parsing_number_literals_and_binexps() {
+  parse_test_wrap_ast! { ".2", exst!(FloatLiteral(0.2)) };
+  parse_test_wrap_ast! { "8.1", exst!(FloatLiteral(8.1)) };
+
+  parse_test_wrap_ast! { "0b010", exst!(NatLiteral(2)) };
+  parse_test_wrap_ast! { "0b0_1_0_", exst!(NatLiteral(2)) }
+
+  parse_test_wrap_ast! {"0xff", exst!(NatLiteral(255)) };
+  parse_test_wrap_ast! {"0xf_f_", exst!(NatLiteral(255)) };
+
+  parse_test_wrap_ast! {"0xf_f_+1", exst!(binexp!("+", NatLiteral(255), NatLiteral(1))) };
+
+  parse_test! {"3; 4; 4.3", AST(
+    vec![exst!(NatLiteral(3)), exst!(NatLiteral(4)),
+      exst!(FloatLiteral(4.3))])
+  };
+
+  parse_test!("1 + 2 * 3", AST(vec!
+    [
+      exst!(binexp!("+", NatLiteral(1), binexp!("*", NatLiteral(2), NatLiteral(3))))
+    ]));
+
+  parse_test!("1 * 2 + 3", AST(vec!
+    [
+      exst!(binexp!("+", binexp!("*", NatLiteral(1), NatLiteral(2)), NatLiteral(3)))
+    ]));
+
+  parse_test!("1 && 2", AST(vec![exst!(binexp!("&&", NatLiteral(1), NatLiteral(2)))]));
+
+  parse_test!("1 + 2 * 3 + 4", AST(vec![exst!(
+    binexp!("+",
+      binexp!("+", NatLiteral(1), binexp!("*", NatLiteral(2), NatLiteral(3))),
+      NatLiteral(4)))]));
+
+  parse_test!("(1 + 2) * 3", AST(vec!
+    [exst!(binexp!("*", binexp!("+", NatLiteral(1), NatLiteral(2)), NatLiteral(3)))]));
+
+  parse_test!(".1 + .2", AST(vec![exst!(binexp!("+", FloatLiteral(0.1), FloatLiteral(0.2)))]));
+  parse_test!("1 / 2", AST(vec![exst!(binexp!("/", NatLiteral(1), NatLiteral(2)))]));
+}
+
+#[test]
+fn parsing_tuples() {
+  parse_test!("()", AST(vec![exst!(TupleLiteral(vec![]))]));
+  parse_test!("(\"hella\", 34)", AST(vec![exst!(
+    TupleLiteral(
+      vec![ex!(s r#""hella""#).into(), ex!(s "34").into()]
+    )
+  )]));
+  parse_test!("((1+2), \"slough\")", AST(vec![exst!(TupleLiteral(vec![
+    ex!(binexp!("+", NatLiteral(1), NatLiteral(2))).into(),
+    ex!(StringLiteral(rc!(slough))).into(),
+  ]))]))
+}
+
+#[test]
+fn parsing_identifiers() {
+  parse_test!("a", AST(vec![exst!(val!("a"))]));
+  parse_test!("some_value", AST(vec![exst!(val!("some_value"))]));
+  parse_test!("a + b", AST(vec![exst!(binexp!("+", val!("a"), val!("b")))]));
+  //parse_test!("a[b]", AST(vec![Expression(
+  //parse_test!("a[]", <- TODO THIS NEEDS TO FAIL
+  //parse_test("a()[b]()[d]")
+  //TODO fix this parsing stuff
+  /*
+  parse_test! { "perspicacity()[a]", AST(vec![
+    exst!(Index {
+      indexee: bx!(ex!(Call { f: bx!(ex!(val!("perspicacity"))), arguments: vec![] })),
+      indexers: vec![ex!(val!("a"))]
+    })
+  ]) 
+  }
+  */
+  parse_test!("a[b,c]", AST(vec![exst!(Index { indexee: bx!(ex!(m val!("a"))), indexers: vec![ex!(m val!("b")), ex!(m val!("c"))]} )]));
+
+  parse_test!("None", AST(vec![exst!(val!("None"))]));
+  parse_test!("Pandas {  a: x + y }", AST(vec![
+    exst!(NamedStruct { name: rc!(Pandas), fields: vec![(rc!(a), ex!(m binexp!("+", val!("x"), val!("y"))))]})
+  ]));
+  parse_test! { "Pandas { a: n, b: q, }",
+  AST(vec![
+      exst!(NamedStruct { name: rc!(Pandas), fields:
+        vec![(rc!(a), ex!(m val!("n"))), (rc!(b), ex!(m val!("q")))]
+        }
+      )
+    ])
+  };
+}
+
+#[test]
+fn parsing_complicated_operators() {
+  parse_test!("a <- b", AST(vec![exst!(binexp!("<-", val!("a"), val!("b")))]));
+  parse_test!("a || b", AST(vec![exst!(binexp!("||", val!("a"), val!("b")))]));
+  parse_test!("a<>b", AST(vec![exst!(binexp!("<>", val!("a"), val!("b")))]));
+  parse_test!("a.b.c.d", AST(vec![exst!(binexp!(".",
+                                              binexp!(".",
+                                                binexp!(".", val!("a"), val!("b")),
+                                              val!("c")),
+                                              val!("d")))]));
+  parse_test!("-3", AST(vec![exst!(prefexp!("-", NatLiteral(3)))]));
+  parse_test!("-0.2", AST(vec![exst!(prefexp!("-", FloatLiteral(0.2)))]));
+  parse_test!("!3", AST(vec![exst!(prefexp!("!", NatLiteral(3)))]));
+  parse_test!("a <- -b", AST(vec![exst!(binexp!("<-", val!("a"), prefexp!("-", val!("b"))))]));
+  parse_test!("a <--b", AST(vec![exst!(binexp!("<--", val!("a"), val!("b")))]));
+}
+
+#[test]
+fn parsing_functions() {
+  parse_test!("fn oi()",  AST(vec![Meta::new(Declaration(FuncSig(Signature { name: rc!(oi), operator: false, params: vec![], type_anno: None })))]));
+  parse_test!("oi()", AST(vec![exst!(Call { f: bx!(ex!(m val!("oi"))), arguments: vec![] })]));
+  parse_test!("oi(a, 2 + 2)", AST(vec![exst!(Call
+  { f: bx!(ex!(m val!("oi"))),
+    arguments: vec![inv!(ex!(val!("a"))).into(), inv!(ex!(binexp!("+", NatLiteral(2), NatLiteral(2)))).into()]
+  })]));
+  parse_error!("a(b,,c)");
+
+  parse_test!("fn a(b, c: Int): Int", AST(vec![Meta::new(Declaration(
+    FuncSig(Signature { name: rc!(a), operator: false, params: vec![
+      FormalParam { name: rc!(b), anno: None, default: None },
+      FormalParam { name: rc!(c), anno: Some(ty!("Int")), default: None }
+    ], type_anno: Some(ty!("Int")) })))]));
+
+
+  parse_test!("fn a(x) { x() }", AST(vec![Meta::new(Declaration(
+    FuncDecl(Signature { name: rc!(a), operator: false, params: vec![FormalParam { name: rc!(x), anno: None, default: None }], type_anno: None },
+      vec![exst!(Call { f: bx!(ex!(m val!("x"))), arguments: vec![] })])))]));
+  parse_test!("fn a(x) {\n x() }", AST(vec![Meta::new(Declaration(
+    FuncDecl(Signature { name: rc!(a), operator: false, params: vec![FormalParam { name: rc!(x), anno: None, default: None }], type_anno: None },
+      vec![exst!(Call { f: bx!(ex!(m val!("x"))), arguments: vec![] })])))]));
+
+  let multiline = r#"
+fn a(x) {
+x()
+}
+"#;
+  parse_test!(multiline, AST(vec![Meta::new(Declaration(
+    FuncDecl(Signature { name: rc!(a), operator: false, params: vec![FormalParam { name: rc!(x), default: None, anno: None }], type_anno: None },
+      vec![exst!(Call { f: bx!(ex!(m val!("x"))), arguments: vec![] })])))]));
+  let multiline2 = r#"
+fn a(x) {
+
+x()
+
+}
+"#;
+  parse_test!(multiline2, AST(vec![Meta::new(Declaration(
+    FuncDecl(Signature { name: rc!(a), operator: false, params: vec![FormalParam { name: rc!(x), default: None, anno: None }], type_anno: None },
+      vec![exst!(s "x()")])))]));
+}
+
+#[test]
+fn functions_with_default_args() {
+  parse_test! {
+    "fn func(x: Int, y: Int = 4) { }",
+    AST(vec![
+      Meta::new(Declaration(
+        FuncDecl(Signature { name: rc!(func), operator: false, type_anno: None, params: vec![
+          FormalParam { name: rc!(x), default: None, anno: Some(ty!("Int")) },
+          FormalParam { name: rc!(y), default: Some(ex!(s "4")), anno: Some(ty!("Int")) }
+        ]}, vec![])
+      ))
+    ])
+  };
+}
+
+#[test]
+fn parsing_bools() {
+  parse_test!("false", AST(vec![exst!(BoolLiteral(false))]));
+  parse_test!("true", AST(vec![exst!(BoolLiteral(true))]));
+}
+
+#[test]
+fn parsing_strings() {
+  parse_test!(r#""hello""#, AST(vec![exst!(StringLiteral(rc!(hello)))]));
+}
+
+#[test]
+fn parsing_types() {
+  parse_test!("type Yolo = Yolo", AST(vec![Meta::new(Declaration(TypeDecl { name: tys!("Yolo"), body: TypeBody(vec![UnitStruct(rc!(Yolo))]), mutable: false} ))]));
+  parse_test!("type mut Yolo = Yolo", AST(vec![Meta::new(Declaration(TypeDecl { name: tys!("Yolo"), body: TypeBody(vec![UnitStruct(rc!(Yolo))]), mutable: true} ))]));
+  parse_test!("type alias Sex = Drugs", AST(vec![Meta::new(Declaration(TypeAlias(rc!(Sex), rc!(Drugs))))]));
+  parse_test!("type Sanchez = Miguel | Alejandro(Int, Option<a>) | Esperanza { a: Int, b: String }",
+  AST(vec![Meta::new(Declaration(TypeDecl{
+    name: tys!("Sanchez"),
+    body: TypeBody(vec![
+      UnitStruct(rc!(Miguel)),
+      TupleStruct(rc!(Alejandro), vec![
+        Singleton(TypeSingletonName { name: rc!(Int), params: vec![] }),
+        Singleton(TypeSingletonName { name: rc!(Option), params: vec![Singleton(TypeSingletonName { name: rc!(a), params: vec![] })] }),
+      ]),
+      Record{
+        name: rc!(Esperanza),
+        members: vec![
+          (rc!(a), Singleton(TypeSingletonName { name: rc!(Int), params: vec![] })),
+          (rc!(b), Singleton(TypeSingletonName { name: rc!(String), params: vec![] })),
+        ]
+      }
+    ]),
+    mutable: false
+  }))]));
+
+  parse_test!("type Jorge<a> = Diego | Kike(a)", AST(vec![
+    Meta::new(Declaration(TypeDecl{
+      name: TypeSingletonName { name: rc!(Jorge), params: vec![Singleton(TypeSingletonName { name: rc!(a), params: vec![] })] },
+      body: TypeBody(vec![UnitStruct(rc!(Diego)), TupleStruct(rc!(Kike), vec![Singleton(TypeSingletonName { name: rc!(a), params: vec![] })])]),
+      mutable: false
+    }
+  ))]));
+}
+
+#[test]
+fn parsing_bindings() {
+  parse_test!("let mut a = 10", AST(vec![Meta::new(Declaration(Binding { name: rc!(a), constant: false, type_anno: None, expr: ex!(m NatLiteral(10)) } ))]));
+  parse_test!("let a = 2 + 2", AST(vec![Meta::new(Declaration(Binding { name: rc!(a), constant: true, type_anno: None, expr: ex!(m binexp!("+", NatLiteral(2), NatLiteral(2))) }) )]));
+  parse_test!("let a: Nat = 2 + 2", AST(vec![Meta::new(Declaration(
+    Binding { name: rc!(a), constant: true, type_anno: Some(Singleton(TypeSingletonName { name: rc!(Nat), params: vec![] })),
+    expr: Meta::new(ex!(binexp!("+", NatLiteral(2), NatLiteral(2)))) }
+  ))]));
+}
+
+#[test]
+fn parsing_block_expressions() {
+  parse_test! {
+    "if a() then { b(); c() }", AST(vec![exst!(
+      IfExpression {
+        discriminator: bx! {
+          Discriminator::Simple(ex!(Call { f: bx!(ex!(m val!("a"))), arguments: vec![]}))
+        },
+        body: bx! {
+          IfExpressionBody::SimpleConditional(
+            vec![exst!(Call { f: bx!(ex!(m val!("b"))), arguments: vec![]}), exst!(Call { f: bx!(ex!(m val!("c"))), arguments: vec![] })],
+            None
+          )
+        }
+      }
+    )])
+  };
+
+  parse_test! {
+    "if a() then { b(); c() } else { q }", AST(vec![exst!(
+      IfExpression {
+        discriminator: bx! {
+          Discriminator::Simple(ex!(Call { f: bx!(ex!(m val!("a"))), arguments: vec![]}))
+        },
+        body: bx! {
+          IfExpressionBody::SimpleConditional(
+            vec![exst!(Call { f: bx!(ex!(m val!("b"))), arguments: vec![]}), exst!(Call { f: bx!(ex!(m val!("c"))), arguments: vec![] })],
+            Some(
+              vec![exst!(val!("q"))],
+            )
+          )
+        }
+      }
+    )])
+  };
+
+  /*
+  parse_test!("if a() then { b(); c() }", AST(vec![exst!(
+      IfExpression(bx!(ex!(Call { f: bx!(ex!(val!("a"))), arguments: vec![]})),
+        vec![exst!(Call { f: bx!(ex!(val!("b"))), arguments: vec![]}), exst!(Call { f: bx!(ex!(val!("c"))), arguments: vec![] })],
+        None)
+      )]));
+  parse_test!(r#"
+  if true then {
+    const a = 10
+    b
+  } else {
+    c
+  }"#,
+  AST(vec![exst!(IfExpression(bx!(ex!(BoolLiteral(true))),
+    vec![Declaration(Binding { name: rc!(a), constant: true, expr: ex!(NatLiteral(10)) }),
+          exst!(val!(rc!(b)))],
+    Some(vec![exst!(val!(rc!(c)))])))])
+  );
+
+  parse_test!("if a { b } else { c }", AST(vec![exst!(
+        IfExpression(bx!(ex!(val!("a"))),
+          vec![exst!(val!("b"))],
+          Some(vec![exst!(val!("c"))])))]));
+
+  parse_test!("if (A {a: 1}) { b } else { c }", AST(vec![exst!(
+        IfExpression(bx!(ex!(NamedStruct { name: rc!(A), fields: vec![(rc!(a), ex!(NatLiteral(1)))]})),
+          vec![exst!(val!("b"))],
+          Some(vec![exst!(val!("c"))])))]));
+
+  parse_error!("if A {a: 1} { b } else { c }");
+  */
+}
+#[test]
+fn parsing_interfaces() {
+  parse_test!("interface Unglueable { fn unglue(a: Glue); fn mar(): Glue }", AST(vec![
+    Meta::new(Declaration(Interface {
+      name: rc!(Unglueable),
+      signatures: vec![
+        Signature {
+          name: rc!(unglue),
+          operator: false,
+          params: vec![
+            FormalParam { name: rc!(a), anno: Some(Singleton(TypeSingletonName { name: rc!(Glue), params: vec![] })), default: None }
+          ],
+          type_anno: None
+        },
+        Signature { name: rc!(mar), operator: false, params: vec![], type_anno: Some(Singleton(TypeSingletonName { name: rc!(Glue), params: vec![] })) },
+      ]
+    }))
+  ]));
+}
+
+#[test]
+fn parsing_impls() {
+  parse_test!("impl Heh { fn yolo(); fn swagg(); }", AST(vec![
+    Meta::new(
+    Declaration(Impl {
+      type_name: ty!("Heh"),
+      interface_name: None,
+      block: vec![
+        FuncSig(Signature { name: rc!(yolo), operator: false, params: vec![], type_anno: None }),
+        FuncSig(Signature { name: rc!(swagg), operator: false, params: vec![], type_anno: None })
+      ] }))]));
+
+  parse_test!("impl Mondai for Lollerino { fn yolo(); fn swagg(); }", AST(vec![
+    Meta::new(Declaration(Impl {
+      type_name: ty!("Lollerino"),
+      interface_name: Some(TypeSingletonName { name: rc!(Mondai), params: vec![] }),
+      block: vec![
+        FuncSig(Signature { name: rc!(yolo), operator: false, params: vec![], type_anno: None}),
+        FuncSig(Signature { name: rc!(swagg), operator: false, params: vec![], type_anno: None })
+      ] }))]));
+
+  parse_test!("impl Hella<T> for (Alpha, Omega) { }", AST(vec![
+    Meta::new(Declaration(Impl {
+      type_name: Tuple(vec![ty!("Alpha"), ty!("Omega")]),
+      interface_name: Some(TypeSingletonName { name: rc!(Hella), params: vec![ty!("T")] }),
+      block: vec![]
+    }))
+  ]));
+
+  parse_test!("impl Option<WTFMate> { fn oi() }", AST(vec![
+    Meta::new(
+    Declaration(Impl {
+      type_name: Singleton(TypeSingletonName { name: rc!(Option), params: vec![ty!("WTFMate")]}),
+      interface_name: None,
+      block: vec![
+        FuncSig(Signature { name: rc!(oi), operator: false, params: vec![], type_anno: None }),
+      ]
+    }))]));
+}
+
+#[test]
+fn parsing_type_annotations() {
+  parse_test!("let a = b : Int", AST(vec![
+    Meta::new(
+    Declaration(Binding { name: rc!(a), constant: true, type_anno: None, expr:
+      ex!(m val!("b"), ty!("Int")) }))]));
+
+  parse_test!("a : Int", AST(vec![
+    exst!(val!("a"), ty!("Int"))
+  ]));
+
+  parse_test!("a : Option<Int>", AST(vec![
+    exst!(val!("a"), Singleton(TypeSingletonName { name: rc!(Option), params: vec![ty!("Int")] }))
+  ]));
+
+  parse_test!("a : KoreanBBQSpecifier<Kimchi, Option<Bulgogi> >", AST(vec![
+    exst!(val!("a"), Singleton(TypeSingletonName { name: rc!(KoreanBBQSpecifier), params: vec![
+      ty!("Kimchi"), Singleton(TypeSingletonName { name: rc!(Option), params: vec![ty!("Bulgogi")] })
+    ] }))
+  ]));
+
+  parse_test!("a : (Int, Yolo<a>)", AST(vec![
+    exst!(val!("a"), Tuple(
+      vec![ty!("Int"), Singleton(TypeSingletonName {
+        name: rc!(Yolo), params: vec![ty!("a")]
+      })]))]));
+}
+
+#[test]
+fn parsing_lambdas() {
+  parse_test_wrap_ast! { r#"\(x) { x + 1}"#, exst!(
+      Lambda { params: vec![FormalParam { name: rc!(x), anno: None, default: None } ], type_anno: None, body: vec![exst!(s "x + 1")] }
+    )
+  }
+
+  parse_test!(r#"\  (x: Int, y) { a;b;c;}"#, AST(vec![
+    exst!(Lambda {
+      params: vec![
+        FormalParam { name: rc!(x), anno: Some(ty!("Int")), default: None },
+        FormalParam { name: rc!(y), anno: None, default: None }
+      ],
+      type_anno: None,
+      body: vec![exst!(s "a"), exst!(s "b"), exst!(s "c")]
+    })
+  ]));
+
+  parse_test!(r#"\(x){y}(1)"#, AST(vec![
+    exst!(Call { f: bx!(ex!(m
+      Lambda {
+        params: vec![
+          FormalParam { name: rc!(x), anno: None, default: None }
+        ],
+        type_anno: None,
+        body: vec![exst!(s "y")] }
+      )),
+      arguments: vec![inv!(ex!(NatLiteral(1))).into()] })]));
+
+  parse_test_wrap_ast! {
+    r#"\(x: Int): String { "q" }"#,
+    exst!(Lambda {
+      params: vec![
+        FormalParam { name: rc!(x), anno: Some(ty!("Int")), default: None },
+      ],
+      type_anno: Some(ty!("String")),
+      body: vec![exst!(s r#""q""#)]
+    })
+  }
+}
+
+#[test]
+fn single_param_lambda() {
+  parse_test_wrap_ast! {
+    r"\x { x + 10 }",
+    exst!(Lambda {
+      params: vec![FormalParam { name: rc!(x), anno: None, default: None }],
+      type_anno: None,
+      body: vec![exst!(s r"x + 10")]
+    })
+  }
+
+  parse_test_wrap_ast! {
+    r"\x: Nat { x + 10 }",
+    exst!(Lambda {
+      params: vec![FormalParam { name: rc!(x), anno: Some(ty!("Nat")), default: None }],
+      type_anno: None,
+      body: vec![exst!(s r"x + 10")]
+    })
+  }
+}
+
+#[test]
+fn more_advanced_lambdas() {
+  parse_test! {
+    r#"fn wahoo() { let a = 10; \(x) { x + a } };
+    wahoo()(3) "#,  AST(vec![
+      exst!(s r"fn wahoo() { let a = 10; \(x) { x + a } }"),
+      exst! {
+        Call {
+          f: bx!(ex!(m Call { f: bx!(ex!(m val!("wahoo"))), arguments: vec![] })),
+          arguments: vec![inv!(ex!(NatLiteral(3))).into()],
+        }
+      }
+    ])
+  }
+}
+
+#[test]
+  fn list_literals() {
+    parse_test! {
+      "[1,2]", AST(vec![
+        exst!(ListLiteral(vec![ex!(m NatLiteral(1)), ex!(m NatLiteral(2))]))])
+    };
+  }
+
+#[test]
+fn while_expr() {
+  parse_test! {
+    "while { }", AST(vec![
+    exst!(WhileExpression { condition: None, body: vec![] })])
+  }
+
+  parse_test! {
+    "while a == b { }", AST(vec![
+    exst!(WhileExpression { condition: Some(bx![ex![m binexp!("==", val!("a"), val!("b"))]]), body: vec![] })])
+  }
+}
+
+#[test]
+fn for_expr() {
+  parse_test! {
+    "for { a <- maybeValue } return 1", AST(vec![
+    exst!(ForExpression {
+      enumerators: vec![Enumerator { id: rc!(a), generator: ex!(m val!("maybeValue")) }],
+      body: bx!(MonadicReturn(Meta::new(ex!(s "1"))))
+    })])
+  }
+
+  parse_test! {
+    "for n <- someRange { f(n); }", AST(vec![
+    exst!(ForExpression { enumerators: vec![Enumerator { id: rc!(n), generator: ex!(m val!("someRange"))}],
+      body: bx!(ForBody::StatementBlock(vec![exst!(s "f(n)")]))
+    })])
+  }
+}
+
+#[test]
+fn patterns() {
+  parse_test_wrap_ast! {
+    "if x is Some(a) then { 4 } else { 9 }", exst!(
+      IfExpression {
+        discriminator: bx!(Discriminator::Simple(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch(Pattern::TupleStruct(rc!(Some), vec![Pattern::Literal(PatternLiteral::VarPattern(rc!(a)))]), vec![exst!(s "4")], Some(vec![exst!(s "9")]))) }
+      )
+  }
+
+  parse_test_wrap_ast! {
+    "if x is Some(a) then 4 else 9", exst!(
+      IfExpression {
+        discriminator: bx!(Discriminator::Simple(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch(Pattern::TupleStruct(rc!(Some), vec![Pattern::Literal(PatternLiteral::VarPattern(rc!(a)))]), vec![exst!(s "4")], Some(vec![exst!(s "9")]))) }
+    )
+  }
+
+  parse_test_wrap_ast! {
+    "if x is Something { a, b: x } then { 4 } else { 9 }", exst!(
+      IfExpression {
+        discriminator: bx!(Discriminator::Simple(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch(
+            Pattern::Record(rc!(Something), vec![
+              (rc!(a),Pattern::Literal(PatternLiteral::StringPattern(rc!(a)))),
+              (rc!(b),Pattern::Literal(PatternLiteral::VarPattern(rc!(x)))) 
+            ]),
+            vec![exst!(s "4")], Some(vec![exst!(s "9")]))) 
+      }
+    )
+  }
+}
+
+#[test]
+fn pattern_literals() {
+  parse_test_wrap_ast! {
+    "if x is -1 then 1 else 2",
+    exst!(
+      IfExpression {
+        discriminator: bx!(Discriminator::Simple(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch(
+          Pattern::Literal(PatternLiteral::NumPattern { neg: true, num: NatLiteral(1) }),
+          vec![exst!(NatLiteral(1))],
+          Some(vec![exst!(NatLiteral(2))]),
+        ))
+      }
+    )
+  }
+
+  parse_test_wrap_ast! {
+    "if x is 1 then 1 else 2", 
+    exst!(
+      IfExpression {
+        discriminator: bx!(Discriminator::Simple(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch(
+            Pattern::Literal(PatternLiteral::NumPattern { neg: false, num: NatLiteral(1) }),
+            vec![exst!(s "1")],
+            Some(vec![exst!(s "2")]),
+            ))
+      }
+    )
+  }
+
+  parse_test! {
+    "if x is true then 1 else 2", AST(vec![
+      exst!(
+        IfExpression {
+          discriminator: bx!(Discriminator::Simple(ex!(s "x"))),
+          body: bx!(IfExpressionBody::SimplePatternMatch(
+            Pattern::Literal(PatternLiteral::BoolPattern(true)),
+            vec![exst!(NatLiteral(1))],
+            Some(vec![exst!(NatLiteral(2))]),
+          ))
+        }
+      )
+    ])
+  }
+
+  parse_test_wrap_ast! {
+    "if x is \"gnosticism\" then 1 else 2",
+      exst!(
+        IfExpression {
+          discriminator: bx!(Discriminator::Simple(ex!(s "x"))),
+          body: bx!(IfExpressionBody::SimplePatternMatch(
+              Pattern::Literal(PatternLiteral::StringPattern(rc!(gnosticism))),
+              vec![exst!(s "1")],
+              Some(vec![exst!(s "2")]),
+              ))
+        }
+      )
+  }
+}

schala-lang/language/src/reduced_ast.rs

@@ -118,10 +118,21 @@ fn reduce_block(block: &Block, symbol_table: &SymbolTable) -> Vec<Stmt> {
   block.iter().map(|stmt| stmt.node().reduce(symbol_table)).collect()
 }
 
+impl InvocationArgument {
+  fn reduce(&self, symbol_table: &SymbolTable) -> Expr {
+    use crate::ast::InvocationArgument::*;
+    match self {
+      Positional(ex) => ex.reduce(symbol_table),
+      Keyword { .. } => Expr::UnimplementedSigilValue,
+      Ignored => Expr::UnimplementedSigilValue,
+    }
+  }
+}
+
 impl Expression {
   fn reduce(&self, symbol_table: &SymbolTable) -> Expr {
-    use crate::ast::ExpressionType::*;
-    let ref input = self.0;
+    use crate::ast::ExpressionKind::*;
+    let ref input = self.kind;
     match input {
       NatLiteral(n) => Expr::Lit(Lit::Nat(*n)),
       FloatLiteral(f) => Expr::Lit(Lit::Float(*f)),
@@ -138,10 +149,7 @@ impl Expression {
         },
         _ => Expr::Val(name.clone()),
       },
-      Call { f, arguments } => Expr::Call {
-        f: Box::new(f.reduce(symbol_table)),
-        args: arguments.iter().map(|arg| arg.node().reduce(symbol_table)).collect(),
-      },
+      Call { f, arguments } =>  reduce_call_expression(f, arguments, symbol_table),
       TupleLiteral(exprs) => Expr::Tuple(exprs.iter().map(|e| e.node().reduce(symbol_table)).collect()),
       IfExpression { discriminator, body } => reduce_if_expression(discriminator, body, symbol_table),
       Lambda { params, body, .. } => reduce_lambda(params, body, symbol_table),
@@ -157,11 +165,18 @@ impl Expression {
 fn reduce_lambda(params: &Vec<FormalParam>, body: &Block, symbol_table: &SymbolTable) -> Expr {
   Expr::Func(Func::UserDefined {
     name: None,
-    params: params.iter().map(|param| param.0.clone()).collect(),
+    params: params.iter().map(|param| param.name.clone()).collect(),
     body: reduce_block(body, symbol_table),
   })
 }
 
+fn reduce_call_expression(func: &Meta<Expression>, arguments: &Vec<Meta<InvocationArgument>>, symbol_table: &SymbolTable) -> Expr {
+  Expr::Call {
+    f: Box::new(func.node().reduce(symbol_table)),
+    args: arguments.iter().map(|arg| arg.node().reduce(symbol_table)).collect(),
+  }
+}
+
 fn reduce_if_expression(discriminator: &Discriminator, body: &IfExpressionBody, symbol_table: &SymbolTable) -> Expr {
   let cond = Box::new(match *discriminator {
     Discriminator::Simple(ref expr) => expr.reduce(symbol_table),
@@ -294,10 +309,10 @@ impl PatternLiteral {
     match self {
       NumPattern { neg, num } => {
         let comparison = Expr::Lit(match (neg, num) {
-          (false, ExpressionType::NatLiteral(n)) => Lit::Nat(*n),
-          (false, ExpressionType::FloatLiteral(f)) => Lit::Float(*f),
-          (true, ExpressionType::NatLiteral(n)) => Lit::Int(-1*(*n as i64)),
-          (true, ExpressionType::FloatLiteral(f)) => Lit::Float(-1.0*f),
+          (false, ExpressionKind::NatLiteral(n)) => Lit::Nat(*n),
+          (false, ExpressionKind::FloatLiteral(f)) => Lit::Float(*f),
+          (true, ExpressionKind::NatLiteral(n)) => Lit::Int(-1*(*n as i64)),
+          (true, ExpressionKind::FloatLiteral(f)) => Lit::Float(-1.0*f),
           _ => panic!("This should never happen")
         });
         let guard = Some(Expr::Call {
@@ -356,14 +371,13 @@ impl PatternLiteral {
 impl Declaration {
   fn reduce(&self, symbol_table: &SymbolTable) -> Stmt {
     use self::Declaration::*;
-    use crate::ast::Signature;
     match self {
-      Binding {name, constant, expr } => Stmt::Binding { name: name.clone(), constant: *constant, expr: expr.reduce(symbol_table) },
+      Binding {name, constant, expr, .. } => Stmt::Binding { name: name.clone(), constant: *constant, expr: expr.node().reduce(symbol_table) },
       FuncDecl(Signature { name, params, .. }, statements) => Stmt::PreBinding {
         name: name.clone(),
         func: Func::UserDefined {
           name: Some(name.clone()),
-          params: params.iter().map(|param| param.0.clone()).collect(),
+          params: params.iter().map(|param| param.name.clone()).collect(),
           body: reduce_block(&statements, symbol_table),
         }
       },
@@ -377,7 +391,7 @@ impl Declaration {
 }
 
 impl BinOp {
-  fn reduce(&self, symbol_table: &SymbolTable, lhs: &Box<Node<Expression>>, rhs: &Box<Node<Expression>>) -> Expr {
+  fn reduce(&self, symbol_table: &SymbolTable, lhs: &Box<Meta<Expression>>, rhs: &Box<Meta<Expression>>) -> Expr {
     if **self.sigil() == "=" {
       Expr::Assign {
         val: Box::new(lhs.node().reduce(symbol_table)),
@@ -391,7 +405,7 @@ impl BinOp {
 }
 
 impl PrefixOp {
-  fn reduce(&self, symbol_table: &SymbolTable, arg: &Box<Node<Expression>>) -> Expr {
+  fn reduce(&self, symbol_table: &SymbolTable, arg: &Box<Meta<Expression>>) -> Expr {
     let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
     Expr::Call { f, args: vec![arg.node().reduce(symbol_table)]}
   }

schala-lang/language/src/schala.rs

@@ -0,0 +1,305 @@
+use stopwatch::Stopwatch;
+
+use std::time::Duration;
+use std::cell::RefCell;
+use std::rc::Rc;
+use std::collections::HashSet;
+
+use itertools::Itertools;
+use schala_repl::{ProgrammingLanguageInterface,
+ComputationRequest, ComputationResponse,
+LangMetaRequest, LangMetaResponse, GlobalOutputStats,
+DebugResponse, DebugAsk};
+use crate::{ast, reduced_ast, tokenizing, parsing, eval, typechecking, symbol_table};
+
+/// All the state necessary to parse and execute a Schala program are stored in this struct.
+/// `state` represents the execution state for the AST-walking interpreter, the other fields
+/// should be self-explanatory.
+pub struct Schala {
+  source_reference: SourceReference,
+  state: eval::State<'static>,
+  symbol_table: Rc<RefCell<symbol_table::SymbolTable>>,
+  type_context: typechecking::TypeContext<'static>,
+  active_parser: Option<parsing::Parser>,
+}
+
+impl Schala {
+  fn handle_docs(&self, source: String) -> LangMetaResponse {
+    LangMetaResponse::Docs {
+      doc_string: format!("Schala item `{}` : <<Schala-lang documentation not yet implemented>>", source)
+    }
+  }
+}
+
+impl Schala {
+  /// Creates a new Schala environment *without* any prelude.
+  fn new_blank_env() -> Schala {
+    let symbols = Rc::new(RefCell::new(symbol_table::SymbolTable::new()));
+    Schala {
+      source_reference: SourceReference::new(),
+      symbol_table: symbols.clone(),
+      state: eval::State::new(symbols),
+      type_context: typechecking::TypeContext::new(),
+      active_parser: None,
+    }
+  }
+
+  /// Creates a new Schala environment with the standard prelude, which is defined as ordinary
+  /// Schala code in the file `prelude.schala`
+  pub fn new() -> Schala {
+    let prelude = include_str!("prelude.schala");
+    let mut s = Schala::new_blank_env();
+
+    let request = ComputationRequest { source: prelude, debug_requests: HashSet::default() };
+    s.run_computation(request);
+    s
+  }
+
+  fn handle_debug_immediate(&self, request: DebugAsk) -> DebugResponse {
+    use DebugAsk::*;
+    match request {
+      Timing => DebugResponse { ask: Timing, value: format!("Invalid") },
+      ByStage { stage_name, token } => match &stage_name[..] {
+        "symbol-table" => {
+          let value = self.symbol_table.borrow().debug_symbol_table();
+          DebugResponse {
+            ask: ByStage { stage_name: format!("symbol-table"), token },
+            value
+          }
+        },
+        s => {
+          DebugResponse {
+            ask: ByStage { stage_name: s.to_string(), token: None },
+            value: format!("Not-implemented")
+          }
+        }
+      }
+    }
+  }
+}
+
+fn tokenizing(input: &str, _handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<Vec<tokenizing::Token>, String> {
+  let tokens = tokenizing::tokenize(input);
+  comp.map(|comp| {
+    let token_string = tokens.iter().map(|t| t.to_string_with_metadata()).join(", ");
+    comp.add_artifact(token_string);
+  });
+
+  let errors: Vec<String> = tokens.iter().filter_map(|t| t.get_error()).collect();
+  if errors.len() == 0 {
+    Ok(tokens)
+  } else {
+    Err(format!("{:?}", errors))
+  }
+}
+
+fn parsing(input: Vec<tokenizing::Token>, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
+  use crate::parsing::Parser;
+
+  let mut parser = handle.active_parser.take().unwrap_or_else(|| Parser::new(input));
+  let ast = parser.parse();
+  let trace = parser.format_parse_trace();
+
+  comp.map(|comp| {
+    let debug_info = match comp.parsing.as_ref().unwrap_or(&ParsingDebugType::CompactAST) {
+      ParsingDebugType::CompactAST => format!("{:?}", ast),
+      ParsingDebugType::ExpandedAST => format!("{:#?}", ast),
+      ParsingDebugType::Trace => format!("{}", trace[0]) //TODO fix this
+    };
+    comp.add_artifact(debug_info);
+  });
+  ast.map_err(|err| format_parse_error(err, handle))
+}
+
+fn format_parse_error(error: parsing::ParseError, handle: &mut Schala) -> String {
+  let line_num = error.token.line_num;
+  let ch = error.token.char_num;
+  let line_from_program = handle.source_reference.get_line(line_num);
+  let location_pointer = format!("{}^", " ".repeat(ch));
+
+  let line_num_digits = format!("{}", line_num).chars().count();
+  let space_padding = " ".repeat(line_num_digits);
+
+  format!(r#"
+{error_msg}
+{space_padding} |
+{line_num} | {}
+{space_padding} | {}
+"#, line_from_program, location_pointer, error_msg=error.msg, space_padding=space_padding, line_num=line_num)
+}
+
+fn symbol_table(input: ast::AST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
+  handle.symbol_table.borrow_mut().add_top_level_symbols(&input).map(|()| {
+    comp.map(|comp| {
+      let debug = handle.symbol_table.borrow().debug_symbol_table();
+      comp.add_artifact(debug);
+    });
+    input
+  })
+}
+
+fn typechecking(input: ast::AST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
+  let result = handle.type_context.typecheck(&input);
+
+  comp.map(|comp| {
+    comp.add_artifact(match result {
+      Ok(ty) => ty.to_string(),
+      Err(err) => format!("Type error: {}", err.msg)
+    });
+  });
+
+  Ok(input)
+}
+
+fn ast_reducing(input: ast::AST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<reduced_ast::ReducedAST, String> {
+  let ref symbol_table = handle.symbol_table.borrow();
+  let output = input.reduce(symbol_table);
+  comp.map(|comp| comp.add_artifact(format!("{:?}", output)));
+  Ok(output)
+}
+
+fn eval(input: reduced_ast::ReducedAST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<String, String> {
+  comp.map(|comp| comp.add_artifact(handle.state.debug_print()));
+  let evaluation_outputs = handle.state.evaluate(input, true);
+  let text_output: Result<Vec<String>, String> = evaluation_outputs
+    .into_iter()
+    .collect();
+
+  let eval_output: Result<String, String> = text_output
+    .map(|v| { v.into_iter().intersperse(format!("\n")).collect() });
+  eval_output
+}
+
+/// Represents lines of source code
+struct SourceReference {
+  lines: Option<Vec<String>>
+}
+
+impl SourceReference {
+  fn new() -> SourceReference {
+    SourceReference { lines: None }
+  }
+
+  fn load_new_source(&mut self, source: &str) {
+    //TODO this is a lot of heap allocations - maybe there's a way to make it more efficient?
+    self.lines = Some(source.lines().map(|s| s.to_string()).collect()); }
+
+  fn get_line(&self, line: usize) -> String {
+    self.lines.as_ref().and_then(|x| x.get(line).map(|s| s.to_string())).unwrap_or(format!("NO LINE FOUND"))
+  }
+}
+
+enum ParsingDebugType {
+  CompactAST,
+  ExpandedAST,
+  Trace
+}
+
+#[derive(Default)]
+struct PassDebugArtifact {
+  parsing: Option<ParsingDebugType>,
+  artifacts: Vec<String>
+
+}
+impl PassDebugArtifact {
+  fn add_artifact(&mut self, artifact: String) {
+    self.artifacts.push(artifact)
+  }
+}
+
+fn stage_names() -> Vec<&'static str> {
+  vec![
+    "tokenizing",
+    "parsing",
+    "symbol-table",
+    "typechecking",
+    "ast-reduction",
+    "ast-walking-evaluation"
+  ]
+}
+
+
+impl ProgrammingLanguageInterface for Schala {
+  fn get_language_name(&self) -> String { format!("Schala") }
+  fn get_source_file_suffix(&self) -> String { format!("schala") }
+
+  fn run_computation(&mut self, request: ComputationRequest) -> ComputationResponse {
+    struct PassToken<'a> {
+      schala: &'a mut Schala,
+      stage_durations: &'a mut Vec<(String, Duration)>,
+      sw: &'a Stopwatch,
+      debug_requests: &'a HashSet<DebugAsk>,
+      debug_responses: &'a mut Vec<DebugResponse>,
+    }
+
+    fn output_wrapper<Input, Output, F>(n: usize, func: F, input: Input, token: &mut PassToken) -> Result<Output, String>
+      where F: Fn(Input, &mut Schala, Option<&mut PassDebugArtifact>) -> Result<Output, String>
+    {
+      let stage_names = stage_names();
+      let cur_stage_name = stage_names[n];
+      let ask = token.debug_requests.iter().find(|ask| ask.is_for_stage(cur_stage_name));
+      let mut debug_artifact = ask.and_then(|ask| match ask {
+        DebugAsk::ByStage { token, .. } => token.as_ref(),
+        _ => None
+      }).map(|token| {
+        let parsing = if cur_stage_name != "parsing" {
+          None
+        } else {
+          Some(match &token[..] {
+            "compact" => ParsingDebugType::CompactAST,
+            "expanded" => ParsingDebugType::ExpandedAST,
+            "trace" => ParsingDebugType::Trace,
+            _ => ParsingDebugType::CompactAST,
+          })
+        };
+        PassDebugArtifact { parsing, ..Default::default() }
+      });
+      let output = func(input, token.schala, debug_artifact.as_mut());
+
+      token.stage_durations.push((cur_stage_name.to_string(), token.sw.elapsed()));
+      if let Some(artifact) = debug_artifact {
+        for value in artifact.artifacts.into_iter() {
+          let resp = DebugResponse { ask: ask.unwrap().clone(), value };
+          token.debug_responses.push(resp);
+        }
+      }
+      output
+    }
+
+    let ComputationRequest { source, debug_requests } = request;
+    self.source_reference.load_new_source(source);
+    let sw = Stopwatch::start_new();
+    let mut stage_durations = Vec::new();
+    let mut debug_responses = Vec::new();
+    let mut tok = PassToken { schala: self, stage_durations: &mut stage_durations, sw: &sw, debug_requests: &debug_requests, debug_responses: &mut debug_responses };
+
+    let main_output: Result<String, String> = Ok(source)
+      .and_then(|source| output_wrapper(0, tokenizing, source, &mut tok))
+      .and_then(|tokens| output_wrapper(1, parsing, tokens, &mut tok))
+      .and_then(|ast| output_wrapper(2, symbol_table, ast, &mut tok))
+      .and_then(|ast| output_wrapper(3, typechecking, ast, &mut tok))
+      .and_then(|ast| output_wrapper(4, ast_reducing, ast, &mut tok))
+      .and_then(|reduced_ast| output_wrapper(5, eval, reduced_ast, &mut tok));
+
+    let total_duration = sw.elapsed();
+    let global_output_stats = GlobalOutputStats {
+      total_duration, stage_durations
+    };
+
+    ComputationResponse {
+      main_output,
+      global_output_stats,
+      debug_responses,
+    }
+  }
+
+  fn request_meta(&mut self, request: LangMetaRequest) -> LangMetaResponse {
+    match request {
+      LangMetaRequest::StageNames => LangMetaResponse::StageNames(stage_names().iter().map(|s| s.to_string()).collect()),
+      LangMetaRequest::Docs { source } => self.handle_docs(source),
+      LangMetaRequest::ImmediateDebug(debug_request) =>
+        LangMetaResponse::ImmediateDebug(self.handle_debug_immediate(debug_request)),
+      LangMetaRequest::Custom { .. } => LangMetaResponse::Custom { kind: format!("not-implemented"), value: format!("") }
+    }
+  }
+}

schala-lang/language/src/symbol_table.rs

@@ -1,32 +1,68 @@
 use std::collections::HashMap;
+use std::collections::hash_map::Entry;
 use std::rc::Rc;
 use std::fmt;
 use std::fmt::Write;
 
 use crate::ast;
-use crate::ast::{TypeBody, TypeSingletonName, Signature};
+use crate::ast::{Meta, TypeBody, TypeSingletonName, Signature, Statement};
 use crate::typechecking::TypeName;
 
+type LineNumber = u32;
+type SymbolTrackTable = HashMap<Rc<String>, LineNumber>;
+
+#[derive(PartialEq, Eq, Hash, Debug)]
+struct PathToSymbol(Vec<Rc<String>>);
+
+#[derive(Debug, Clone)]
+struct ScopeSegment {
+  scope_name: Rc<String>,
+  scope_type: ScopeSegmentKind,
+}
+
+#[derive(Debug, Clone)]
+enum ScopeSegmentKind {
+  Function,
+  //Type,
+}
+
 //cf. p. 150 or so of Language Implementation Patterns
 pub struct SymbolTable {
-  pub values: HashMap<Rc<String>, Symbol> //TODO this will eventually have real type information
+  values: HashMap<PathToSymbol, Symbol>,
 }
 
-//TODO add various types of lookups here, maybe multiple hash tables internally? also make values
-//non-public
+//TODO add various types of lookups here, maybe multiple hash tables internally?
 impl SymbolTable {
   pub fn new() -> SymbolTable {
-    SymbolTable { values: HashMap::new() }
+    SymbolTable {
+      values: HashMap::new(),
+    }
+  }
+
+  fn add_new_symbol(&mut self, name: &Rc<String>, scope_path: &Vec<ScopeSegment>, spec: SymbolSpec) {
+    let mut vec: Vec<Rc<String>> = scope_path.iter().map(|segment| segment.scope_name.clone()).collect();
+    vec.push(name.clone());
+    let symbol_path = PathToSymbol(vec);
+    let symbol = Symbol { name: name.clone(), scopes: scope_path.to_vec(), spec };
+    self.values.insert(symbol_path, symbol);
   }
 
   pub fn lookup_by_name(&self, name: &Rc<String>) -> Option<&Symbol> {
-    self.values.get(name)
+    self.lookup_by_path(name, &vec![])
+  }
+
+  pub fn lookup_by_path(&self, name: &Rc<String>, path: &Vec<Rc<String>>) -> Option<&Symbol> {
+    let mut vec = path.clone();
+    vec.push(name.clone());
+    let symbol_path = PathToSymbol(vec);
+    self.values.get(&symbol_path)
   }
 }
 
 #[derive(Debug)]
 pub struct Symbol {
-  pub name: Rc<String>,
+  pub name: Rc<String>, //TODO does this need to be pub?
+  scopes: Vec<ScopeSegment>,
   pub spec: SymbolSpec,
 }
 
@@ -46,7 +82,8 @@ pub enum SymbolSpec {
   },
   RecordConstructor {
     fields: HashMap<Rc<String>, Rc<String>>
-  }
+  },
+  Binding
 }
 
 impl fmt::Display for SymbolSpec {
@@ -55,7 +92,8 @@ impl fmt::Display for SymbolSpec {
     match self {
       Func(type_names) => write!(f, "Func({:?})", type_names),
       DataConstructor { index, type_name, type_args } => write!(f, "DataConstructor(idx: {})({:?} -> {})", index, type_args, type_name),
-      RecordConstructor { fields } => write!(f, "RecordConstructor( <fields> )"),
+      RecordConstructor { fields: _fields } => write!(f, "RecordConstructor( <fields> )"),
+      Binding => write!(f, "Binding"),
     }
   }
 }
@@ -63,15 +101,58 @@ impl fmt::Display for SymbolSpec {
 impl SymbolTable {
   /* note: this adds names for *forward reference* but doesn't actually create any types. solve that problem
    * later */
+
   pub fn add_top_level_symbols(&mut self, ast: &ast::AST) -> Result<(), String> {
-    use self::ast::Statement;
+    let mut scope_name_stack = Vec::new();
+    self.add_symbols_from_scope(&ast.0, &mut scope_name_stack)
+  }
+
+  fn add_symbols_from_scope<'a>(&'a mut self, statements: &Vec<Meta<Statement>>, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
     use self::ast::Declaration::*;
-    for statement in ast.0.iter() {
-      let statement = statement.node();
+
+    fn insert_and_check_duplicate_symbol(table: &mut SymbolTrackTable, name: &Rc<String>) -> Result<(), String> {
+      match table.entry(name.clone()) {
+        Entry::Occupied(o) => {
+          let line_number = o.get(); //TODO make this actually work
+          Err(format!("Duplicate definition: {}. It's already defined at {}", name, line_number))
+        },
+        Entry::Vacant(v) => {
+          let line_number = 0; //TODO should work
+          v.insert(line_number);
+          Ok(())
+        }
+      }
+    }
+
+    let mut seen_identifiers: SymbolTrackTable = HashMap::new();
+
+    for meta in statements.iter() {
+      let statement = meta.node();
       if let Statement::Declaration(decl) = statement {
         match decl {
-          FuncSig(signature) | FuncDecl(signature, _) => self.add_function_signature(signature)?,
-          TypeDecl { name, body, mutable } => self.add_type_decl(name, body, mutable)?,
+          FuncSig(ref signature) => {
+            insert_and_check_duplicate_symbol(&mut seen_identifiers, &signature.name)?;
+            self.add_function_signature(signature, scope_name_stack)?
+          }
+          FuncDecl(ref signature, ref body) => {
+            insert_and_check_duplicate_symbol(&mut seen_identifiers, &signature.name)?;
+            self.add_function_signature(signature, scope_name_stack)?;
+            scope_name_stack.push(ScopeSegment{
+              scope_name: signature.name.clone(),
+              scope_type: ScopeSegmentKind::Function,
+            });
+            let output = self.add_symbols_from_scope(body, scope_name_stack);
+            let _ = scope_name_stack.pop();
+            output?
+          },
+          TypeDecl { name, body, mutable } => {
+            insert_and_check_duplicate_symbol(&mut seen_identifiers, &name.name)?;
+            self.add_type_decl(name, body, mutable, scope_name_stack)?
+          },
+          Binding { name, .. } => {
+            insert_and_check_duplicate_symbol(&mut seen_identifiers, name)?;
+            self.add_new_symbol(name, scope_name_stack, SymbolSpec::Binding);
+          }
           _ => ()
         }
       }
@@ -81,29 +162,27 @@ impl SymbolTable {
   pub fn debug_symbol_table(&self) -> String {
     let mut output = format!("Symbol table\n");
     for (name, sym) in &self.values {
-      write!(output, "{} -> {}\n", name, sym).unwrap();
+      write!(output, "{:?} -> {}\n", name, sym).unwrap();
     }
     output
   }
 
-  fn add_function_signature(&mut self, signature: &Signature) -> Result<(), String> {
+  fn add_function_signature(&mut self, signature: &Signature, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
     let mut local_type_context = LocalTypeContext::new();
-    let types = signature.params.iter().map(|param| match param {
-      (_, Some(type_identifier)) => Rc::new(format!("{:?}", type_identifier)),
-      (_, None) => local_type_context.new_universal_type()
+    let types = signature.params.iter().map(|param| match param.anno {
+      Some(ref type_identifier) => Rc::new(format!("{:?}", type_identifier)),
+      None => local_type_context.new_universal_type()
     }).collect();
-    let spec = SymbolSpec::Func(types);
-    self.values.insert(
-      signature.name.clone(),
-      Symbol { name: signature.name.clone(), spec }
-    );
+    self.add_new_symbol(&signature.name, scope_name_stack, SymbolSpec::Func(types));
     Ok(())
   }
 
-  fn add_type_decl(&mut self, type_name: &TypeSingletonName, body: &TypeBody, _mutable: &bool) -> Result<(), String> {
+  fn add_type_decl(&mut self, type_name: &TypeSingletonName, body: &TypeBody, _mutable: &bool, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
     use crate::ast::{TypeIdentifier, Variant};
     let TypeBody(variants) = body;
     let TypeSingletonName { name, .. } = type_name;
+    //scope_name_stack.push(name.clone()); //TODO adding this makes variants scoped under their
+    //type name and breaks a lot of things - don't add it until importing names works
     //TODO figure out why _params isn't being used here
     for (index, var) in variants.iter().enumerate() {
       match var {
@@ -113,7 +192,7 @@ impl SymbolTable {
             type_name: name.clone(),
             type_args: vec![],
           };
-          self.values.insert(variant_name.clone(), Symbol { name: variant_name.clone(), spec });
+          self.add_new_symbol(variant_name, scope_name_stack, spec);
         },
         Variant::TupleStruct(variant_name, tuple_members) => {
           let type_args = tuple_members.iter().map(|type_name| match type_name {
@@ -125,19 +204,18 @@ impl SymbolTable {
             type_name: name.clone(),
             type_args
           };
-          let symbol = Symbol { name: variant_name.clone(), spec };
-          self.values.insert(variant_name.clone(), symbol);
+          self.add_new_symbol(variant_name, scope_name_stack, spec);
         },
         //TODO if there is only one variant, and it is a record, it doesn't need to have an
         //explicit name
-        Variant::Record { name, members } => {
+        Variant::Record { name, members: _members } => {
           let fields = HashMap::new();
           let spec = SymbolSpec::RecordConstructor { fields };
-          let symbol = Symbol { name: name.clone(), spec };
-          self.values.insert(name.clone(), symbol);
+          self.add_new_symbol(name, scope_name_stack, spec);
         },
       }
     }
+    //scope_name_stack.pop();
     Ok(())
   }
 }
@@ -156,3 +234,158 @@ impl LocalTypeContext {
     Rc::new(format!("{}", (('a' as u8) + n) as char))
   }
 }
+
+
+#[cfg(test)]
+mod symbol_table_tests {
+  use super::*;
+  use crate::util::quick_ast;
+
+  macro_rules! values_in_table {
+    //TODO multiple values
+    ($source:expr, $single_value:expr) => {
+      {
+      let mut symbol_table = SymbolTable::new();
+      let ast = quick_ast($source);
+      symbol_table.add_top_level_symbols(&ast).unwrap();
+      match symbol_table.lookup_by_name($single_value) {
+        Some(_spec) => (),
+        None => panic!(),
+      };
+      }
+    }
+  }
+
+  #[test]
+  fn basic_symbol_table() {
+    values_in_table! { "let a = 10; fn b() { 20 }", &rc!(b) };
+  }
+
+  #[test]
+  fn no_duplicates() {
+    let source = r#"
+    fn a() { 1 }
+    fn b() { 2 }
+    fn a() { 3 }
+    "#;
+    let mut symbol_table = SymbolTable::new();
+    let ast = quick_ast(source);
+    let output = symbol_table.add_top_level_symbols(&ast).unwrap_err();
+    assert!(output.contains("Duplicate"))
+  }
+
+  #[test]
+  fn no_duplicates_2() {
+    let source = r#"
+    let a = 20;
+    let q = 39;
+    let a = 30;
+    "#;
+    let mut symbol_table = SymbolTable::new();
+    let ast = quick_ast(source);
+    let output = symbol_table.add_top_level_symbols(&ast).unwrap_err();
+    assert!(output.contains("Duplicate"))
+  }
+
+  #[test]
+  fn no_duplicates_3() {
+    let source = r#"
+    fn a() {
+      let a = 20
+      let b = 40
+      a + b
+    }
+
+    fn q() {
+      let x = 30
+      let x = 33
+    }
+    "#;
+    let mut symbol_table = SymbolTable::new();
+    let ast = quick_ast(source);
+    let output = symbol_table.add_top_level_symbols(&ast).unwrap_err();
+    assert!(output.contains("Duplicate"))
+  }
+
+  #[test]
+  fn dont_falsely_detect_duplicates() {
+    let source = r#"
+    let a = 20;
+    fn some_func() {
+      let a = 40;
+      77
+    }
+    let q = 39;
+    "#;
+    let mut symbol_table = SymbolTable::new();
+    let ast = quick_ast(source);
+    symbol_table.add_top_level_symbols(&ast).unwrap();
+    assert!(symbol_table.lookup_by_path(&rc!(a), &vec![]).is_some());
+    assert!(symbol_table.lookup_by_path(&rc!(a), &vec![rc!(some_func)]).is_some());
+  }
+
+  #[test]
+  fn enclosing_scopes() {
+    let source = r#"
+fn outer_func(x) {
+  fn inner_func(arg) {
+    arg
+  }
+  x + inner_func(x)
+}"#;
+    let mut symbol_table = SymbolTable::new();
+    let ast = quick_ast(source);
+    symbol_table.add_top_level_symbols(&ast).unwrap();
+    assert!(symbol_table.lookup_by_path(&rc!(outer_func), &vec![]).is_some());
+    assert!(symbol_table.lookup_by_path(&rc!(inner_func), &vec![rc!(outer_func)]).is_some());
+  }
+
+  #[test]
+  fn enclosing_scopes_2() {
+    let source = r#"
+fn outer_func(x) {
+  fn inner_func(arg) {
+    arg
+  }
+
+  fn second_inner_func() {
+    fn another_inner_func() {
+    }
+  }
+
+  inner_func(x)
+}"#;
+    let mut symbol_table = SymbolTable::new();
+    let ast = quick_ast(source);
+    symbol_table.add_top_level_symbols(&ast).unwrap();
+    println!("{}", symbol_table.debug_symbol_table());
+    assert!(symbol_table.lookup_by_path(&rc!(outer_func), &vec![]).is_some());
+    assert!(symbol_table.lookup_by_path(&rc!(inner_func), &vec![rc!(outer_func)]).is_some());
+    assert!(symbol_table.lookup_by_path(&rc!(second_inner_func), &vec![rc!(outer_func)]).is_some());
+    assert!(symbol_table.lookup_by_path(&rc!(another_inner_func), &vec![rc!(outer_func), rc!(second_inner_func)]).is_some());
+  }
+
+  #[test]
+  fn enclosing_scopes_3() {
+    let source = r#"
+fn outer_func(x) {
+  fn inner_func(arg) {
+    arg
+  }
+
+  fn second_inner_func() {
+    fn another_inner_func() {
+    }
+    fn another_inner_func() {
+    }
+  }
+
+  inner_func(x)
+}"#;
+    let mut symbol_table = SymbolTable::new();
+    let ast = quick_ast(source);
+    let output = symbol_table.add_top_level_symbols(&ast).unwrap_err();
+    assert!(output.contains("Duplicate"))
+  }
+}
+

schala-lang/language/src/tokenizing.rs

@@ -15,7 +15,7 @@ pub enum TokenKind {
   Pipe, Backslash,
 
   Comma, Period, Colon, Underscore,
-  Slash,
+  Slash, Equals,
 
   Operator(Rc<String>),
   DigitGroup(Rc<String>), HexLiteral(Rc<String>), BinNumberSigil,
@@ -118,7 +118,7 @@ type CharData = (usize, usize, char);
 pub fn tokenize(input: &str) -> Vec<Token> {
   let mut tokens: Vec<Token> = Vec::new();
 
-  let mut input  = input.lines().enumerate()
+  let mut input = input.lines().enumerate()
       .intersperse((0, "\n"))
       .flat_map(|(line_idx, ref line)| {
           line.chars().enumerate().map(move |(ch_idx, ch)| (line_idx, ch_idx, ch))
@@ -238,7 +238,7 @@ fn handle_alphabetic(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>
 
 fn handle_operator(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenKind {
   match c {
-    '<' | '>' | '|' | '.' => {
+    '<' | '>' | '|' | '.' | '=' => {
       let ref next = input.peek().map(|&(_, _, c)| { c });
       if !next.map(|n| { is_operator(&n) }).unwrap_or(false) {
         return match c {
@@ -246,6 +246,7 @@ fn handle_operator(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>)
           '>' => RAngleBracket,
           '|' => Pipe,
           '.' => Period,
+          '=' => Equals,
           _ => unreachable!(),
         }
       }
@@ -298,7 +299,7 @@ mod schala_tokenizer_tests {
     let a = tokenize("let a: A<B> = c ++ d");
     let token_kinds: Vec<TokenKind> = a.into_iter().map(move |t| t.kind).collect();
     assert_eq!(token_kinds, vec![Keyword(Let), ident!("a"), Colon, ident!("A"),
-      LAngleBracket, ident!("B"), RAngleBracket, op!("="), ident!("c"), op!("++"), ident!("d")]);
+      LAngleBracket, ident!("B"), RAngleBracket, Equals, ident!("c"), op!("++"), ident!("d")]);
   }
 
   #[test]

schala-lang/language/src/typechecking.rs

@@ -1,27 +1,146 @@
 use std::rc::Rc;
+use std::fmt::Write;
+
+use ena::unify::{UnifyKey, InPlaceUnificationTable, UnificationTable, EqUnifyValue};
 
 use crate::ast::*;
 use crate::util::ScopeStack;
+use crate::builtin::{PrefixOp, BinOp};
+
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct TypeData {
+  ty: Option<Type>
+}
+
+impl TypeData {
+  pub fn new() -> TypeData {
+    TypeData { ty: None }
+  }
+}
 
 pub type TypeName = Rc<String>;
 
 pub struct TypeContext<'a> {
-  variable_map: ScopeStack<'a, Rc<String>, Type<TVar>>,
-  evar_count: u32
+  variable_map: ScopeStack<'a, Rc<String>, Type>,
+  unification_table: InPlaceUnificationTable<TypeVar>,
 }
 
 /// `InferResult` is the monad in which type inference takes place.
 type InferResult<T> = Result<T, TypeError>;
 
 #[derive(Debug, Clone)]
-struct TypeError { msg: String }
+pub struct TypeError { pub msg: String }
 
 impl TypeError {
-  fn new<A>(msg: &str) -> InferResult<A> {
-    Err(TypeError { msg: msg.to_string() })
+  fn new<A, T>(msg: T) -> InferResult<A> where T: Into<String> {
+    Err(TypeError { msg: msg.into() })
   }
 }
 
+#[derive(Debug, Clone, PartialEq)]
+pub enum Type {
+  Const(TypeConst),
+  Var(TypeVar),
+  Arrow {
+    params: Vec<Type>,
+    ret: Box<Type>
+  },
+  Compound {
+    ty_name: String,
+    args:Vec<Type>
+  }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeVar(usize);
+
+impl UnifyKey for TypeVar {
+  type Value = Option<TypeConst>;
+  fn index(&self) -> u32 { self.0 as u32 }
+  fn from_index(u: u32) -> TypeVar { TypeVar(u as usize) }
+  fn tag() -> &'static str { "TypeVar" }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum TypeConst {
+  Unit,
+  Nat,
+  Int,
+  Float,
+  StringT,
+  Bool,
+  Ordering,
+  //UserDefined
+}
+
+impl TypeConst {
+  pub fn to_string(&self) -> String {
+    use self::TypeConst::*;
+    match self {
+      Unit => format!("()"),
+      Nat => format!("Nat"),
+      Int => format!("Int"),
+      Float => format!("Float"),
+      StringT => format!("String"),
+      Bool => format!("Bool"),
+      Ordering => format!("Ordering"),
+    }
+  }
+}
+
+impl EqUnifyValue for TypeConst { }
+
+macro_rules! ty {
+  ($type_name:ident) => { Type::Const(TypeConst::$type_name) };
+  ($t1:ident -> $t2:ident) => { Type::Arrow { params: vec![ty!($t1)], ret: box ty!($t2) } };
+  ($t1:ident -> $t2:ident -> $t3:ident) => { Type::Arrow { params: vec![ty!($t1), ty!($t2)], ret: box ty!($t3) } };
+  ($type_list:ident, $ret_type:ident) => {
+    Type::Arrow {
+      params: $type_list,
+      ret: box $ret_type,
+    }
+  }
+}
+
+//TODO find a better way to capture the to/from string logic
+impl Type {
+  pub fn to_string(&self) -> String {
+    use self::Type::*;
+    match self {
+      Const(c) => c.to_string(),
+      Var(v) => format!("t_{}", v.0),
+      Arrow { params, box ref ret } => {
+        if params.len() == 0 {
+          format!("-> {}", ret.to_string())
+        } else {
+          let mut buf = String::new();
+          for p in params.iter() {
+            write!(buf, "{} -> ", p.to_string()).unwrap();
+          }
+          write!(buf, "{}", ret.to_string()).unwrap();
+          buf
+        }
+      },
+      Compound { .. } => format!("<some compound type>")
+    }
+  }
+
+  fn from_string(string: &str) -> Option<Type> {
+    Some(match string {
+      "()" | "Unit" => ty!(Unit),
+      "Nat" => ty!(Nat),
+      "Int" => ty!(Int),
+      "Float" => ty!(Float),
+      "String" => ty!(StringT),
+      "Bool" => ty!(Bool),
+      "Ordering" => ty!(Ordering),
+      _ => return None
+    })
+  }
+}
+
+/*
 /// `Type` is parameterized by whether the type variables can be just universal, or universal or
 /// existential.
 #[derive(Debug, Clone)]
@@ -104,151 +223,258 @@ impl TConst {
     TConst::User(Rc::new(name.to_string()))
   }
 }
+*/
 
 impl<'a> TypeContext<'a> {
   pub fn new() -> TypeContext<'a> {
     TypeContext { 
       variable_map: ScopeStack::new(None),
-      evar_count: 0
+      unification_table: UnificationTable::new(),
     }
   }
 
-  pub fn typecheck(&mut self, ast: &AST) -> Result<String, String> {
-    match self.infer_ast(ast) {
-      Ok(t) => Ok(format!("{:?}", t)),
-      Err(err) => Err(format!("Type error: {:?}", err))
-    }
-  }
-}
+  /*
+  fn new_env(&'a self, new_var: Rc<String>, ty: Type) -> TypeContext<'a> {
+    let mut new_context = TypeContext {
+      variable_map: self.variable_map.new_scope(None),
+      unification_table: UnificationTable::new(), //???? not sure if i want this
+    };
 
-impl<'a> TypeContext<'a> {
-  fn infer_ast(&mut self, ast: &AST) -> InferResult<Type<UVar>> {
-    self.infer_block(&ast.0)
+    new_context.variable_map.insert(new_var, ty);
+    new_context
   }
+  */
 
-  fn infer_statement(&mut self, stmt: &Statement) -> InferResult<Type<UVar>> {
-    match stmt {
-      Statement::ExpressionStatement(ref expr) => self.infer_expr(expr.node()),
-      Statement::Declaration(ref decl) => self.infer_decl(decl),
-    }
-  }
 
-  fn infer_expr(&mut self, expr: &Expression) -> InferResult<Type<UVar>> {
-    match expr {
-      Expression(expr_type, Some(type_anno)) => {
-        let tx = self.infer_expr_type(expr_type)?;
-        let ty = type_anno.to_monotype();
-        self.unify(&ty.to_tvar(), &tx.to_tvar()).map(|x| x.skolemize())
-      },
-      Expression(expr_type, None) => self.infer_expr_type(expr_type)
-    }
-  }
-
-  fn infer_decl(&mut self, _decl: &Declaration) -> InferResult<Type<UVar>> {
-    Ok(Type::Const(TConst::user("unimplemented")))
-  }
-
-  fn infer_expr_type(&mut self, expr_type: &ExpressionType) -> InferResult<Type<UVar>> {
-    use self::ExpressionType::*;
-    Ok(match expr_type {
-      NatLiteral(_) => Type::Const(TConst::Nat),
-      FloatLiteral(_) => Type::Const(TConst::Float),
-      StringLiteral(_) => Type::Const(TConst::StringT),
-      BoolLiteral(_) => Type::Const(TConst::Bool),
-      Value(name) => {
-        //TODO handle the distinction between 0-arg constructors and variables at some point
-        // need symbol table for that
-        match self.variable_map.lookup(name) {
-          Some(ty) => ty.clone().skolemize(),
-          None => return TypeError::new(&format!("Variable {} not found", name))
+  fn get_type_from_name(&self, name: &TypeIdentifier) -> InferResult<Type> {
+    use self::TypeIdentifier::*;
+    Ok(match name {
+      Singleton(TypeSingletonName { name,.. }) =>  {
+        match Type::from_string(&name) {
+          Some(ty) => ty,
+          None => return TypeError::new(format!("Unknown type name: {}", name))
         }
       },
-      IfExpression { discriminator, body } => self.infer_if_expr(discriminator, body)?,
-      Call { f, arguments } => {
-        let tf = self.infer_expr(f)?; //has to be an Arrow Type
-        let targ = self.infer_expr(&arguments[0].node())?; // TODO make this work with functions with more than one arg
-        match tf {
-          Type::Arrow(t1, t2) => {
-            self.unify(&t1.to_tvar(), &targ.to_tvar())?;
-            *t2.clone()
-          },
-          _ => return TypeError::new("not a function")
-        }
-      },
-
-      Lambda { params, .. } => {
-
-        let _arg_type = match &params[0] {
-          (_, Some(type_anno)) => type_anno.to_monotype().to_tvar(),
-          (_, None) => self.allocate_existential(),
-        };
-        //let _result_type = unimplemented!();
-        return TypeError::new("Unimplemented");
-
-        //Type::Arrow(Box::new(arg_type), Box::new(result_type))
-      }
-      _ => Type::Const(TConst::user("unimplemented"))
+      Tuple(_) => return TypeError::new("tuples aren't ready yet"),
     })
   }
 
-  fn infer_if_expr(&mut self, discriminator: &Discriminator, body: &IfExpressionBody) -> InferResult<Type<UVar>> {
-    let _test = match discriminator {
-      Discriminator::Simple(expr) => expr,
-      _ => return TypeError::new("Dame desu")
-    };
-
-    let (_then_clause, _maybe_else_clause) = match body {
-      IfExpressionBody::SimpleConditional(a, b) => (a, b),
-      _ => return TypeError::new("Dont work")
-    };
-
-    TypeError::new("Not implemented")
+  /// `typecheck` is the entry into the type-inference system, accepting an AST as an argument
+  /// Following the example of GHC, the compiler deliberately does typechecking before de-sugaring
+  /// the AST to ReducedAST
+  pub fn typecheck(&mut self, ast: &AST) -> Result<Type, TypeError> {
+    let mut returned_type = Type::Const(TypeConst::Unit);
+    for statement in ast.0.iter() {
+      returned_type = self.statement(statement.node())?;
+    }
+    Ok(returned_type)
   }
 
-  fn infer_block(&mut self, block: &Block) -> InferResult<Type<UVar>> {
-    let mut output = Type::Const(TConst::Unit);
-    for statement in block.iter() {
-      output = self.infer_statement(statement.node())?;
+  fn statement(&mut self, statement: &Statement) -> InferResult<Type> {
+    match statement {
+      Statement::ExpressionStatement(e) => self.expr(e.node()),
+      Statement::Declaration(decl) => self.decl(decl),
+    }
+  }
+
+  fn decl(&mut self, decl: &Declaration) -> InferResult<Type> {
+    use self::Declaration::*;
+    match decl {
+      Binding { name, expr, .. } => {
+        let ty = self.expr(expr.node())?;
+        self.variable_map.insert(name.clone(), ty);
+      },
+      _ => (),
+    }
+    Ok(ty!(Unit))
+  }
+
+  fn invoc(&mut self, invoc: &InvocationArgument) -> InferResult<Type> {
+    use InvocationArgument::*;
+    match invoc {
+      Positional(expr) => self.expr(expr),
+      _ => Ok(ty!(Nat)) //TODO this is wrong
+    }
+  }
+
+  fn expr(&mut self, expr: &Expression) -> InferResult<Type> {
+    match expr {
+      Expression { kind, type_anno: Some(anno) } => {
+        let t1 = self.expr_type(kind)?;
+        let t2 = self.get_type_from_name(anno)?;
+        self.unify(t2, t1)
+      },
+      Expression { kind, type_anno: None } => self.expr_type(kind)
+    }
+  }
+
+  fn expr_type(&mut self, expr: &ExpressionKind) -> InferResult<Type> {
+    use self::ExpressionKind::*;
+    Ok(match expr {
+      NatLiteral(_) => ty!(Nat),
+      BoolLiteral(_) => ty!(Bool),
+      FloatLiteral(_) => ty!(Float),
+      StringLiteral(_) => ty!(StringT),
+      PrefixExp(op, expr) => self.prefix(op, expr.node())?,
+      BinExp(op, lhs, rhs) => self.binexp(op, lhs.node(), rhs.node())?,
+      IfExpression { discriminator, body } => self.if_expr(discriminator, body)?,
+      Value(val) => self.handle_value(val)?,
+      Call { box ref f, arguments } => self.call(f.node(), arguments)?,
+      Lambda { params, type_anno, body } => self.lambda(params, type_anno, body)?,
+      _ => ty!(Unit),
+    })
+  }
+
+  fn prefix(&mut self, op: &PrefixOp, expr: &Expression) -> InferResult<Type> {
+    let tf = match op.get_type() {
+      Ok(ty) => ty,
+      Err(e) => return TypeError::new(e)
+    };
+
+    let tx = self.expr(expr)?;
+    self.handle_apply(tf, vec![tx])
+  }
+
+  fn binexp(&mut self, op: &BinOp, lhs: &Expression, rhs: &Expression) -> InferResult<Type> {
+    let tf = match op.get_type() {
+      Ok(ty) => ty,
+      Err(e) => return TypeError::new(e),
+    };
+
+    let t_lhs = self.expr(lhs)?;
+    let t_rhs = self.expr(rhs)?; //TODO is this order a problem? not sure
+
+    self.handle_apply(tf, vec![t_lhs, t_rhs])
+  }
+
+  fn if_expr(&mut self, discriminator: &Discriminator, body: &IfExpressionBody) -> InferResult<Type> {
+    use self::Discriminator::*; use self::IfExpressionBody::*;
+    match (discriminator, body) {
+      (Simple(expr), SimpleConditional(then_clause, else_clause)) => self.handle_simple_if(expr, then_clause, else_clause),
+      _ => TypeError::new(format!("Complex conditionals not supported"))
+    }
+  }
+
+  fn handle_simple_if(&mut self, expr: &Expression, then_clause: &Block, else_clause: &Option<Block>) -> InferResult<Type> {
+    let t1 = self.expr(expr)?;
+    let t2 = self.block(then_clause)?;
+    let t3 = match else_clause {
+      Some(block) => self.block(block)?,
+      None => ty!(Unit)
+    };
+
+    let _ = self.unify(ty!(Bool), t1)?;
+    self.unify(t2, t3)
+  }
+
+  fn lambda(&mut self, params: &Vec<FormalParam>, type_anno: &Option<TypeIdentifier>, _body: &Block) -> InferResult<Type> {
+    let argument_types: InferResult<Vec<Type>> = params.iter().map(|param: &FormalParam| {
+      if let FormalParam { anno: Some(type_identifier), ..  } = param {
+        self.get_type_from_name(type_identifier)
+      } else {
+        Ok(Type::Var(self.fresh_type_variable()))
+      }
+    }).collect();
+    let argument_types = argument_types?;
+    let ret_type = match type_anno.as_ref() {
+      Some(anno) => self.get_type_from_name(anno)?,
+      None => Type::Var(self.fresh_type_variable())
+    };
+
+    Ok(ty!(argument_types, ret_type))
+  }
+
+  fn call(&mut self, f: &Expression, args: &Vec<Meta<InvocationArgument>>) -> InferResult<Type> {
+    let tf = self.expr(f)?;
+    let arg_types: InferResult<Vec<Type>> = args.iter().map(|ex| self.invoc(ex.node())).collect();
+    let arg_types = arg_types?;
+    self.handle_apply(tf, arg_types)
+  }
+
+  fn handle_apply(&mut self, tf: Type, args: Vec<Type>) -> InferResult<Type> {
+    Ok(match tf {
+      Type::Arrow { ref params, ret: box ref t_ret } if params.len() == args.len() => {
+        for (t_param, t_arg) in params.iter().zip(args.iter()) {
+          let _ = self.unify(t_param.clone(), t_arg.clone())?; //TODO I think this needs to reference a sub-scope
+        }
+        t_ret.clone()
+      },
+      Type::Arrow { .. } => return TypeError::new("Wrong length"),
+      _ => return TypeError::new(format!("Not a function"))
+    })
+  }
+
+  fn block(&mut self, block: &Block) -> InferResult<Type> {
+    let mut output = ty!(Unit);
+    for s in block.iter() {
+      let statement = s.node();
+      output = self.statement(statement)?;
     }
     Ok(output)
   }
 
-  fn unify(&mut self, _t1: &Type<TVar>, _t2: &Type<TVar>) -> InferResult<Type<TVar>> {
-    TypeError::new("not implemented")
+  fn handle_value(&mut self, val: &Rc<String>) -> InferResult<Type> {
+    match self.variable_map.lookup(val) {
+      Some(ty) => Ok(ty.clone()),
+      None => TypeError::new(format!("Couldn't find variable: {}", val))
+    }
   }
 
-  fn allocate_existential(&mut self) -> Type<TVar> {
-    let n = self.evar_count;
-    self.evar_count += 1;
-    Type::Var(TVar::Exist(ExistentialVar(n)))
+  fn unify(&mut self, t1: Type, t2: Type) -> InferResult<Type> {
+    use self::Type::*;
+
+    match (t1, t2) {
+      (Const(ref c1), Const(ref c2)) if c1 == c2 => Ok(Const(c1.clone())), //choice of c1 is arbitrary I *think*
+      (a @ Var(_), b @ Const(_)) => self.unify(b, a),
+      (Const(ref c1), Var(ref v2)) => {
+        self.unification_table.unify_var_value(v2.clone(), Some(c1.clone()))
+          .or_else(|_| TypeError::new(format!("Couldn't unify {:?} and {:?}", Const(c1.clone()), Var(*v2))))?;
+        Ok(Const(c1.clone()))
+      },
+      (Var(v1), Var(v2)) => {
+        //TODO add occurs check
+        self.unification_table.unify_var_var(v1.clone(), v2.clone())
+          .or_else(|e| {
+            println!("Unify error: {:?}", e);
+            TypeError::new(format!("Two type variables {:?} and {:?} couldn't unify", v1, v2))
+          })?;
+        Ok(Var(v1.clone())) //arbitrary decision I think
+      },
+      (a, b) => TypeError::new(format!("{:?} and {:?} do not unify", a, b)),
+    }
+  }
+
+  fn fresh_type_variable(&mut self) -> TypeVar {
+    let new_type_var = self.unification_table.new_key(None);
+    new_type_var
   }
 }
 
 #[cfg(test)]
-mod tests {
+mod typechecking_tests {
   use super::*;
 
-  fn parse(input: &str) -> AST {
-    let tokens: Vec<crate::tokenizing::Token> = crate::tokenizing::tokenize(input);
-    let mut parser = crate::parsing::Parser::new(tokens);
-    parser.parse().unwrap()
-  }
-
-  macro_rules! type_test {
-    ($input:expr, $correct:expr) => {
-      {
+  macro_rules! assert_type_in_fresh_context {
+    ($string:expr, $type:expr) => {
       let mut tc = TypeContext::new();
-      let ast = parse($input);
-      tc.add_symbols(&ast);
-      assert_eq!($correct, tc.type_check(&ast).unwrap())
-      }
+      let ref ast = crate::util::quick_ast($string);
+      let ty = tc.typecheck(ast).unwrap();
+      assert_eq!(ty, $type)
     }
   }
 
-
+  #[test]
+  fn basic_test() {
+    assert_type_in_fresh_context!("1", ty!(Nat));
+    assert_type_in_fresh_context!(r#""drugs""#, ty!(StringT));
+    assert_type_in_fresh_context!("true", ty!(Bool));
+    assert_type_in_fresh_context!("-1", ty!(Int));
+  }
 
   #[test]
-  fn basic_inference() {
-
+  fn operators() {
+    assert_type_in_fresh_context!("1 + 2", ty!(Nat));
+    assert_type_in_fresh_context!("-2", ty!(Int));
+    assert_type_in_fresh_context!("!true", ty!(Bool));
   }
 }

schala-lang/language/src/util.rs

@@ -2,6 +2,10 @@ use std::collections::HashMap;
 use std::hash::Hash;
 use std::cmp::Eq;
 
+macro_rules! bx {
+  ($e:expr) => { Box::new($e) }
+}
+
 #[derive(Default, Debug)]
 pub struct ScopeStack<'a, T: 'a, V: 'a>  where T: Hash + Eq {
   parent: Option<&'a ScopeStack<'a, T, V>>,
@@ -41,3 +45,15 @@ impl<'a, T, V> ScopeStack<'a, T, V> where T: Hash + Eq {
   }
 }
 
+/// this is intended for use in tests, and does no error-handling whatsoever
+#[allow(dead_code)]
+pub fn quick_ast(input: &str) -> crate::ast::AST {
+  let tokens = crate::tokenizing::tokenize(input);
+  let mut parser = crate::parsing::Parser::new(tokens);
+  parser.parse().unwrap()
+}
+
+#[allow(unused_macros)]
+macro_rules! rc {
+  ($string:tt) => { Rc::new(stringify!($string).to_string()) }
+}

schala-lang/language/src/visitor.rs

@@ -0,0 +1,57 @@
+use std::rc::Rc;
+
+use crate::builtin::{BinOp, PrefixOp};
+use crate::ast::{Expression, ExpressionKind, InvocationArgument, Meta};
+
+pub trait ExpressionKindVisitor<T> {
+  fn nat_literal(&mut self, n: &u64) -> T;
+  fn float_literal(&mut self, f: &f64) -> T;
+  fn string_literal(&mut self, s: Rc<String>) -> T;
+  fn bool_literal(&mut self, b: &bool) -> T;
+  fn binexp(&mut self, op: &BinOp, lhs: &Expression, rhs: &Expression) -> T;
+  fn prefix_exp(&mut self, op: &PrefixOp, arg: &Expression) -> T;
+  fn value(&mut self, value_name: Rc<String>) -> T;
+  fn call_expression(&mut self, f: &Expression, arguments: &Vec<Meta<InvocationArgument>>) -> T;
+}
+
+pub fn dispatch<T>(input: &ExpressionKind, visitor: &mut dyn ExpressionKindVisitor<T>) -> T {
+  use ExpressionKind::*;
+  match input {
+    NatLiteral(n) => visitor.nat_literal(n),
+    FloatLiteral(f) => visitor.float_literal(f),
+    StringLiteral(s) => visitor.string_literal(s.clone()),
+    BoolLiteral(b) => visitor.bool_literal(b),
+    BinExp(op, box lhs, box rhs) => visitor.binexp(op, lhs.node(), rhs.node()),
+    PrefixExp(op, box arg) => visitor.prefix_exp(op, arg.node()),
+    Value(val_name) => visitor.value(val_name.clone()),
+    Call { box f, arguments } =>  visitor.call_expression(f.node(), arguments),
+    _ => panic!()
+  }
+}
+
+/*
+struct NumberSummer;
+
+impl ExpressionKindVisitor<u64> for NumberSummer {
+  fn nat_literal(&mut self, n: &u64) -> u64 { n.clone() }
+  fn float_literal(&mut self, f: &f64) -> u64
+  fn string_literal(&mut self, s: Rc<String>) -> u64 { 0 }
+  fn binexp(&mut self, op: &BinOp, lhs: &Expression, rhs: &Expression)  -> u64 {
+    let lhs = dispatch(&lhs.kind, self);
+    let rhs = dispatch(&rhs.kind, self);
+    lhs + rhs
+  }
+}
+
+#[test]
+fn yolo_swagg() {
+  use super::*;
+
+  let mut t = NumberSummer;
+
+  let x = ExpressionKind::NatLiteral(4);
+
+  let result = dispatch(&x, &mut t);
+  assert_eq!(result, 4);
+}
+*/

schala-repl-codegen/Cargo.toml

@@ -1,13 +0,0 @@
-[package]
-name = "schala-repl-codegen"
-version = "0.1.0"
-authors = ["greg <greg.shuflin@protonmail.com>"]
-
-[dependencies]
-syn = { version = "0.15.6", features = ["full", "extra-traits"] }
-quote = "0.6.8"
-proc-macro2 = "0.4.19"
-schala-repl = { path = "../schala-repl" }
-
-[lib]
-proc-macro = true

schala-repl-codegen/src/lib.rs

@@ -1,199 +0,0 @@
-#![feature(trace_macros)]
-#![recursion_limit="128"]
-extern crate proc_macro;
-extern crate proc_macro2;
-#[macro_use]
-extern crate quote;
-extern crate syn;
-
-use proc_macro::TokenStream;
-use syn::{Ident, Attribute, DeriveInput};
-
-fn find_attr_by_name<'a>(name: &str, attrs: &'a Vec<Attribute>) -> Option<&'a Attribute> {
-  attrs.iter().find(|attr| {
-    let first = attr.path.segments.first();
-    let seg: Option<&&syn::PathSegment> = first.as_ref().map(|x| x.value());
-    seg.map(|seg| seg.ident.to_string() == name).unwrap_or(false)
-  })
-}
-
-fn extract_attribute_arg_by_name(name: &str, attrs: &Vec<Attribute>) -> Option<String> {
-  use syn::{Meta, Lit, MetaNameValue};
-  find_attr_by_name(name, attrs)
-  .and_then(|attr| {
-    match attr.interpret_meta() {
-      Some(Meta::NameValue(MetaNameValue { lit: Lit::Str(litstr), .. })) => Some(litstr.value()),
-      _ => None,
-    }
-  })
-}
-
-fn extract_attribute_list(name: &str, attrs: &Vec<Attribute>) -> Option<Vec<(Ident, Option<Vec<Ident>>)>> {
-  use syn::{Meta, MetaList, NestedMeta};
-  find_attr_by_name(name, attrs)
-  .and_then(|attr| {
-    match attr.interpret_meta() {
-      Some(Meta::List(MetaList { nested, .. })) => {
-        Some(nested.iter().map(|nested_meta| match nested_meta {
-          &NestedMeta::Meta(Meta::Word(ref ident)) => (ident.clone(), None),
-          &NestedMeta::Meta(Meta::List(MetaList { ref ident, nested: ref nested2, .. })) => {
-            let own_args = nested2.iter().map(|nested_meta2| match nested_meta2 {
-              &NestedMeta::Meta(Meta::Word(ref ident)) => ident.clone(),
-              _ => panic!("Bad format for doubly-nested attribute list")
-            }).collect();
-            (ident.clone(), Some(own_args))
-          },
-          _ => panic!("Bad format for nested list")
-        }).collect())
-      },
-      _ => panic!("{} must be a comma-delimited list surrounded by parens", name)
-    }
-  })
-}
-
-fn get_attribute_identifier(attr_name: &str, attrs: &Vec<Attribute>) -> Option<proc_macro2::Ident> {
-  find_attr_by_name(attr_name, attrs).and_then(|attr| {
-    let tts = attr.tts.clone().into_iter().collect::<Vec<_>>();
-
-    if tts.len() == 2 {
-      let ref after_equals: proc_macro2::TokenTree = tts[1];
-      match after_equals {
-        proc_macro2::TokenTree::Ident(ident)  => Some(ident.clone()),
-        _ => None
-      }
-    } else {
-      None
-    }
-  })
-}
-
-/* a pass_chain function signature with input A and output B looks like:
- * fn(A, &mut ProgrammingLanguageInterface, Option<&mut DebugHandler>) -> Result<B, String>
- *
- * TODO use some kind of failure-handling library to make this better
- */
-fn generate_pass_chain(idents: Vec<Ident>) -> proc_macro2::TokenStream {
-  let final_return = quote! {
-    {
-      let final_output: FinishedComputation = unfinished_computation.finish(Ok(input_to_next_stage));
-      final_output
-    }
-  };
-
-  let nested_passes = idents.iter()
-    .rev()
-    .fold(final_return, |later_fragment, pass_name| {
-      quote! {
-        {
-          let pass_name = stringify!(#pass_name);
-          let (output, duration) = {
-            let ref debug_map = eval_options.debug_passes;
-            let debug_handle = match debug_map.get(pass_name) {
-              Some(PassDebugOptionsDescriptor { opts }) => {
-                let ptr = &mut unfinished_computation;
-                ptr.cur_debug_options = opts.clone();
-                Some(ptr)
-              }
-              _ => None
-            };
-            let start = time::Instant::now();
-            let pass_output = #pass_name(input_to_next_stage, self, debug_handle);
-            let elapsed = start.elapsed();
-            (pass_output, elapsed)
-          };
-          if eval_options.debug_timing {
-            unfinished_computation.durations.push(duration);
-          }
-          match output {
-            Ok(input_to_next_stage) => #later_fragment,
-            //TODO this error type needs to be guaranteed to provide a useable string
-            Err(err) => return unfinished_computation.output(Err(format!("Pass {} failed:\n{}", pass_name, err))),
-          }
-        }
-      }
-    });
-
-  quote! {
-    {
-      use std::time;
-      use schala_repl::PassDebugOptionsDescriptor;
-
-      let eval_options = options;
-      let input_to_next_stage = input;
-      let mut unfinished_computation = UnfinishedComputation::default();
-      #nested_passes
-    }
-  }
-}
-
-#[proc_macro_derive(ProgrammingLanguageInterface,
-  attributes(LanguageName, SourceFileExtension, PipelineSteps, DocMethod, HandleCustomInterpreterDirectives))]
-pub fn derive_programming_language_interface(input: TokenStream) -> TokenStream {
-  let ast: DeriveInput = syn::parse(input).unwrap();
-  let name = &ast.ident;
-  let attrs = &ast.attrs;
-
-  let language_name: String = extract_attribute_arg_by_name("LanguageName", attrs).expect("LanguageName is required");
-  let file_ext = extract_attribute_arg_by_name("SourceFileExtension", attrs).expect("SourceFileExtension is required");
-  let passes = extract_attribute_list("PipelineSteps", attrs).expect("PipelineSteps are required");
-  let pass_idents = passes.iter().map(|x| x.0.clone());
-
-  let get_doc_impl = match get_attribute_identifier("DocMethod", attrs) {
-    None => quote! { },
-    Some(method_name) => quote! {
-      fn get_doc(&self, commands: &Vec<&str>) -> Option<String> {
-        self.#method_name(commands)
-      }
-    }
-  };
-
-  let handle_custom_interpreter_directives_impl = match get_attribute_identifier("HandleCustomInterpreterDirectives", attrs) {
-    None => quote! { },
-    Some(method_name) => quote! {
-      fn handle_custom_interpreter_directives(&mut self, commands: &Vec<&str>) -> Option<String> {
-        //println!("If #method_name is &self not &mut self, this runs forever");
-        self.#method_name(commands)
-      }
-    }
-  };
-
-  let pass_descriptors = passes.iter().map(|pass| {
-    let name = pass.0.to_string();
-    let opts: Vec<String> = match &pass.1 {
-      None => vec![],
-      Some(opts) => opts.iter().map(|o| o.to_string()).collect(),
-    };
-
-    quote! {
-      PassDescriptor {
-        name: #name.to_string(),
-        debug_options: vec![#(format!(#opts)),*]
-      }
-    }
-  });
-
-  let pass_chain = generate_pass_chain(pass_idents.collect());
-
-  let tokens = quote! {
-    use schala_repl::PassDescriptor;
-    impl ProgrammingLanguageInterface for #name {
-      fn get_language_name(&self) -> String {
-        #language_name.to_string()
-      }
-      fn get_source_file_suffix(&self) -> String {
-        #file_ext.to_string()
-      }
-      fn execute_pipeline(&mut self, input: &str, options: &EvalOptions) -> FinishedComputation {
-        #pass_chain
-      }
-      fn get_passes(&self) -> Vec<PassDescriptor> {
-        vec![ #(#pass_descriptors),* ]
-      }
-      #get_doc_impl
-      #handle_custom_interpreter_directives_impl
-    }
-  };
-
-  let output: TokenStream = tokens.into();
-  output
-}

schala-repl/Cargo.toml

@@ -2,23 +2,22 @@
 name = "schala-repl"
 version = "0.1.0"
 authors = ["greg <greg.shuflin@protonmail.com>"]
+edition = "2018"
 
 [dependencies]
 llvm-sys = "70.0.2"
 take_mut = "0.2.2"
 itertools = "0.5.8"
-getopts = "*"
+getopts = "0.2.18"
 lazy_static = "0.2.8"
 maplit = "*"
-colored = "1.5"
-serde = "1.0.15"
-serde_derive = "1.0.15"
-serde_json = "1.0.3"
-rocket = "0.4.0"
-rocket_contrib = "0.4.0"
+colored = "1.8"
+serde = "1.0.91"
+serde_derive = "1.0.91"
+serde_json = "1.0.15"
 phf = "0.7.12"
 includedir = "0.2.0"
-linefeed = "0.5.0"
+linefeed = "0.6.0"
 regex = "0.2"
 
 [build-dependencies]

schala-repl/src/language.rs

@@ -1,173 +1,80 @@
-use std::collections::HashMap;
-use colored::*;
-use std::fmt::Write;
 use std::time;
-
-#[derive(Debug, Default, Serialize, Deserialize)]
-pub struct EvalOptions {
-  pub execution_method: ExecutionMethod,
-  pub debug_passes: HashMap<String, PassDebugOptionsDescriptor>,
-  pub debug_timing: bool,
-}
-
-#[derive(Debug, Hash, PartialEq)]
-pub struct PassDescriptor {
-  pub name: String,
-  pub debug_options: Vec<String>
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-pub struct PassDebugOptionsDescriptor {
-  pub opts: Vec<String>,
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-pub enum ExecutionMethod {
-  Compile,
-  Interpret,
-}
-impl Default for ExecutionMethod {
-  fn default() -> ExecutionMethod {
-    ExecutionMethod::Interpret
-  }
-}
-
-#[derive(Debug, Default)]
-pub struct UnfinishedComputation {
-  artifacts: Vec<(String, TraceArtifact)>,
-  pub durations: Vec<time::Duration>,
-  pub cur_debug_options: Vec<String>,
-}
-
-#[derive(Debug)]
-pub struct FinishedComputation {
-  artifacts: Vec<(String, TraceArtifact)>,
-  durations: Vec<time::Duration>,
-  text_output: Result<String, String>,
-}
-
-impl UnfinishedComputation {
-  pub fn add_artifact(&mut self, artifact: TraceArtifact) {
-    self.artifacts.push((artifact.stage_name.clone(), artifact));
-  }
-  pub fn finish(self, text_output: Result<String, String>) -> FinishedComputation {
-    FinishedComputation {
-      artifacts: self.artifacts,
-      text_output,
-      durations: self.durations,
-    }
-  }
-  pub fn output(self, output: Result<String, String>) -> FinishedComputation {
-    FinishedComputation {
-      artifacts: self.artifacts,
-      text_output: output,
-      durations: self.durations,
-    }
-  }
-}
-
-impl FinishedComputation {
-
-  fn get_timing(&self) -> Option<String> {
-    if self.durations.len() != 0 {
-      let mut buf = String::new();
-      write!(&mut buf, "Timing: ").unwrap();
-      for duration in self.durations.iter() {
-        let timing = (duration.as_secs() as f64) + (duration.subsec_nanos() as f64 * 1e-9);
-        write!(&mut buf, "{}s, ", timing).unwrap()
-      }
-      write!(&mut buf, "\n").unwrap();
-      Some(buf)
-    } else {
-      None
-    }
-  }
-
-  pub fn to_repl(&self) -> String {
-    let mut buf = String::new();
-    for (stage, artifact) in self.artifacts.iter() {
-      let color = artifact.text_color;
-      let stage = stage.color(color).bold();
-      let output = artifact.debug_output.color(color);
-      write!(&mut buf, "{}: {}\n", stage, output).unwrap();
-    }
-
-    match self.get_timing() {
-      Some(timing) => write!(&mut buf, "{}", timing).unwrap(),
-      None => ()
-    }
-
-    match self.text_output {
-      Ok(ref output) => write!(&mut buf, "{}", output).unwrap(),
-      Err(ref err) => write!(&mut buf, "{} {}", "Error: ".red().bold(), err).unwrap(),
-    }
-    buf
-  }
-  pub fn to_noninteractive(&self) -> Option<String> {
-    match self.text_output {
-      Ok(_) => {
-        let mut buf = String::new();
-        for (stage, artifact) in self.artifacts.iter() {
-          let color = artifact.text_color;
-          let stage = stage.color(color).bold();
-          let output = artifact.debug_output.color(color);
-          write!(&mut buf, "{}: {}\n", stage, output).unwrap();
-        }
-        if buf == "" { None } else { Some(buf) }
-      },
-      Err(ref s) => Some(format!("{} {}", "Error: ".red().bold(), s))
-    }
-  }
-}
-
-#[derive(Debug)]
-pub struct TraceArtifact {
-  stage_name: String,
-  debug_output: String,
-  text_color: &'static str,
-}
-
-impl TraceArtifact {
-  pub fn new(stage: &str, debug: String) -> TraceArtifact {
-    let color = match stage {
-      "parse_trace"  | "ast" => "red",
-      "ast_reducing" => "red",
-      "tokens" => "green",
-      "type_check" => "magenta",
-      _ => "blue",
-    };
-    TraceArtifact { stage_name: stage.to_string(), debug_output: debug, text_color: color}
-  }
-
-  pub fn new_parse_trace(trace: Vec<String>) -> TraceArtifact {
-    let mut output = String::new();
-
-    for t in trace {
-      output.push_str(&t);
-      output.push_str("\n");
-    }
-
-    TraceArtifact { stage_name: "parse_trace".to_string(), debug_output: output, text_color: "red"}
-  }
-}
+use std::collections::HashSet;
 
 pub trait ProgrammingLanguageInterface {
-  fn execute_pipeline(&mut self, _input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
-    FinishedComputation { artifacts: vec![], text_output: Err(format!("Execution pipeline not done")), durations: vec![] }
-  }
-
   fn get_language_name(&self) -> String;
   fn get_source_file_suffix(&self) -> String;
-  fn get_passes(&self) -> Vec<PassDescriptor> {
-    vec![]
+
+  fn run_computation(&mut self, _request: ComputationRequest) -> ComputationResponse {
+    ComputationResponse {
+      main_output: Err(format!("Computation pipeline not implemented")),
+      global_output_stats: GlobalOutputStats::default(),
+      debug_responses: vec![],
+    }
   }
-  fn handle_custom_interpreter_directives(&mut self, _commands: &Vec<&str>) -> Option<String> {
-    None
-  }
-  fn custom_interpreter_directives_help(&self) -> String {
-    format!(">> No custom interpreter directives specified <<")
-  }
-  fn get_doc(&self, _commands: &Vec<&str>) -> Option<String> {
-    None
+
+  fn request_meta(&mut self, _request: LangMetaRequest) -> LangMetaResponse {
+    LangMetaResponse::Custom { kind: format!("not-implemented"), value: format!("") }
   }
 }
+
+pub struct ComputationRequest<'a> {
+  pub source: &'a str,
+  pub debug_requests: HashSet<DebugAsk>,
+}
+
+pub struct ComputationResponse {
+  pub main_output: Result<String, String>,
+  pub global_output_stats: GlobalOutputStats,
+  pub debug_responses: Vec<DebugResponse>,
+}
+
+#[derive(Default, Debug)]
+pub struct GlobalOutputStats {
+  pub total_duration: time::Duration,
+  pub stage_durations: Vec<(String, time::Duration)>
+}
+
+#[derive(Debug, Clone, Hash, Eq, PartialEq, Deserialize, Serialize)]
+pub enum DebugAsk {
+  Timing,
+  ByStage { stage_name: String, token: Option<String> },
+}
+
+impl DebugAsk {
+  pub fn is_for_stage(&self, name: &str) -> bool {
+    match self {
+      DebugAsk::ByStage { stage_name, .. } if stage_name == name => true,
+      _ => false
+    }
+  }
+}
+
+pub struct DebugResponse {
+  pub ask: DebugAsk,
+  pub value: String
+}
+
+pub enum LangMetaRequest {
+  StageNames,
+  Docs {
+    source: String,
+  },
+  Custom {
+    kind: String,
+    value: String
+  },
+  ImmediateDebug(DebugAsk),
+}
+
+pub enum LangMetaResponse {
+  StageNames(Vec<String>),
+  Docs {
+    doc_string: String,
+  },
+  Custom {
+    kind: String,
+    value: String
+  },
+  ImmediateDebug(DebugResponse),
+}

schala-repl/src/lib.rs

@@ -9,88 +9,49 @@ extern crate colored;
 #[macro_use]
 extern crate serde_derive;
 extern crate serde_json;
-#[macro_use]
-extern crate rocket;
-extern crate rocket_contrib;
 extern crate includedir;
 extern crate phf;
 
+use std::collections::HashSet;
 use std::path::Path;
 use std::fs::File;
 use std::io::Read;
 use std::process::exit;
-use std::default::Default;
 
 mod repl;
 mod language;
-mod webapp;
 
-const VERSION_STRING: &'static str = "0.1.0";
+pub use language::{ProgrammingLanguageInterface,
+ComputationRequest, ComputationResponse,
+LangMetaRequest, LangMetaResponse,
+DebugResponse, DebugAsk, GlobalOutputStats};
 
 include!(concat!(env!("OUT_DIR"), "/static.rs"));
+const VERSION_STRING: &'static str = "0.1.0";
 
-pub use language::{ProgrammingLanguageInterface, EvalOptions,
-  ExecutionMethod, TraceArtifact, FinishedComputation, UnfinishedComputation, PassDebugOptionsDescriptor, PassDescriptor};
-
-pub type PLIGenerator = Box<Fn() -> Box<ProgrammingLanguageInterface> + Send + Sync>;
-
-pub fn repl_main(generators: Vec<PLIGenerator>) {
-  let languages: Vec<Box<ProgrammingLanguageInterface>> = generators.iter().map(|x| x()).collect();
-
-  let option_matches = program_options().parse(std::env::args()).unwrap_or_else(|e| {
+pub fn start_repl(langs: Vec<Box<dyn ProgrammingLanguageInterface>>) {
+  let options = command_line_options().parse(std::env::args()).unwrap_or_else(|e| {
     println!("{:?}", e);
     exit(1);
   });
 
-  if option_matches.opt_present("list-languages") {
-    for lang in languages {
-      println!("{}", lang.get_language_name());
-    }
-    exit(1);
-  }
-
-  if option_matches.opt_present("help") {
-    println!("{}", program_options().usage("Schala metainterpreter"));
+  if options.opt_present("help") {
+    println!("{}", command_line_options().usage("Schala metainterpreter"));
     exit(0);
   }
 
-  if option_matches.opt_present("webapp") {
-    webapp::web_main(generators);
-    exit(0);
-  }
-
-  let mut options = EvalOptions::default();
-  let debug_passes = if let Some(opts) = option_matches.opt_str("debug") {
-    let output: Vec<String> = opts.split_terminator(",").map(|s| s.to_string()).collect();
-    output
-  } else {
-    vec![]
-  };
-
-  let language_names: Vec<String> = languages.iter().map(|lang| {lang.get_language_name()}).collect();
-  let initial_index: usize =
-    option_matches.opt_str("lang")
-    .and_then(|lang| { language_names.iter().position(|x| { x.to_lowercase() == lang.to_lowercase() }) })
-    .unwrap_or(0);
-
-  options.execution_method = match option_matches.opt_str("eval-style") {
-    Some(ref s) if s == "compile" => ExecutionMethod::Compile,
-    _ => ExecutionMethod::Interpret,
-  };
-
-  match option_matches.free[..] {
+  match options.free[..] {
     [] | [_] => {
-      let mut repl = repl::Repl::new(languages, initial_index);
-      repl.run();
+      let mut repl = repl::Repl::new(langs);
+      repl.run_repl();
     }
     [_, ref filename, _..] => {
-
-      run_noninteractive(filename, languages, options, debug_passes);
+      run_noninteractive(filename, langs);
     }
   };
 }
 
-fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInterface>>, mut options: EvalOptions, debug_passes: Vec<String>) {
+fn run_noninteractive(filename: &str, languages: Vec<Box<dyn ProgrammingLanguageInterface>>) {
   let path = Path::new(filename);
   let ext = path.extension().and_then(|e| e.to_str()).unwrap_or_else(|| {
     println!("Source file lacks extension");
@@ -104,53 +65,28 @@ fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInte
 
   let mut source_file = File::open(path).unwrap();
   let mut buffer = String::new();
-
   source_file.read_to_string(&mut buffer).unwrap();
 
-  for pass in debug_passes.into_iter() {
-    if let Some(_) = language.get_passes().iter().find(|desc| desc.name == pass) {
-      options.debug_passes.insert(pass, PassDebugOptionsDescriptor { opts: vec![] });
-    }
-  }
+  let request = ComputationRequest {
+    source: &buffer,
+    debug_requests: HashSet::new(),
+  };
 
-  match options.execution_method {
-    ExecutionMethod::Compile => {
-      /*
-      let llvm_bytecode = language.compile(&buffer);
-      compilation_sequence(llvm_bytecode, filename);
-      */
-      panic!("Not ready to go yet");
-    },
-    ExecutionMethod::Interpret => {
-      let output = language.execute_pipeline(&buffer, &options);
-      output.to_noninteractive().map(|text| println!("{}", text));
-    }
-  }
+  let response = language.run_computation(request);
+  match response.main_output {
+    Ok(s) => println!("{}", s),
+    Err(s) => println!("{}", s)
+  };
 }
 
-fn program_options() -> getopts::Options {
+
+fn command_line_options() -> getopts::Options {
   let mut options = getopts::Options::new();
-  options.optopt("s",
-                 "eval-style",
-                 "Specify whether to compile (if supported) or interpret the language. If not specified, the default is language-specific",
-                 "[compile|interpret]"
-                 );
-  options.optflag("",
-                  "list-languages",
-                  "Show a list of all supported languages");
-  options.optopt("l",
-                 "lang",
-                 "Start up REPL in a language",
-                 "LANGUAGE");
   options.optflag("h",
                   "help",
                   "Show help text");
   options.optflag("w",
                   "webapp",
                   "Start up web interpreter");
-  options.optopt("d",
-                  "debug",
-                  "Debug a stage (l = tokenizer, a = AST, r = parse trace, s = symbol table)",
-                  "[l|a|r|s]");
   options
 }

schala-repl/src/repl/command_tree.rs

@@ -1,23 +1,34 @@
+use super::{Repl, InterpreterDirectiveOutput};
+use crate::repl::directive_actions::DirectiveAction;
+use colored::*;
 
+/// A CommandTree is either a `Terminal` or a `NonTerminal`. When command parsing reaches the first
+/// Terminal, it will use the `DirectiveAction` found there to find an appropriate function to execute,
+/// and then execute it with any remaining arguments
 #[derive(Clone)]
 pub enum CommandTree {
   Terminal {
     name: String,
+    children: Vec<CommandTree>,
     help_msg: Option<String>,
-    function: Option<Box<(fn() -> Option<String>)>>,
+    action: DirectiveAction,
   },
   NonTerminal {
     name: String,
     children: Vec<CommandTree>,
     help_msg: Option<String>,
-    function: Option<Box<(fn() -> Option<String>)>>,
+    action: DirectiveAction,
   },
   Top(Vec<CommandTree>),
 }
 
 impl CommandTree {
-  pub fn term(s: &str, help: Option<&str>) -> CommandTree {
-    CommandTree::Terminal {name: s.to_string(), help_msg: help.map(|x| x.to_string()), function: None }
+  pub fn nonterm_no_further_tab_completions(s: &str, help: Option<&str>) -> CommandTree {
+    CommandTree::NonTerminal {name: s.to_string(), help_msg: help.map(|x| x.to_string()), children: vec![], action: DirectiveAction::Null }
+  }
+
+  pub fn terminal(s: &str, help: Option<&str>, children: Vec<CommandTree>, action: DirectiveAction) -> CommandTree {
+    CommandTree::Terminal {name: s.to_string(), help_msg: help.map(|x| x.to_string()), children, action}
   }
 
   pub fn nonterm(s: &str, help: Option<&str>, children: Vec<CommandTree>) -> CommandTree {
@@ -25,7 +36,7 @@ impl CommandTree {
       name: s.to_string(),
       help_msg: help.map(|x| x.to_string()),
       children,
-      function: None,
+      action: DirectiveAction::Null
     }
   }
 
@@ -43,11 +54,46 @@ impl CommandTree {
       CommandTree::Top(_) => ""
     }
   }
-  pub fn get_children(&self) -> Vec<&str> {
+  pub fn get_children(&self) -> &Vec<CommandTree> {
+    use CommandTree::*;
     match self {
-      CommandTree::Terminal { .. } => vec![],
-      CommandTree::NonTerminal { children, .. } => children.iter().map(|x| x.get_cmd()).collect(),
-      CommandTree::Top(children) => children.iter().map(|x| x.get_cmd()).collect(),
+      Terminal { children, .. } |
+      NonTerminal { children, .. } |
+      Top(children) => children
+    }
+  }
+  pub fn get_subcommands(&self) -> Vec<&str> {
+    self.get_children().iter().map(|x| x.get_cmd()).collect()
+  }
+
+  pub fn perform(&self, repl: &mut Repl, arguments: &Vec<&str>) -> InterpreterDirectiveOutput {
+    let mut dir_pointer: &CommandTree = self;
+    let mut idx = 0;
+
+    let res: Result<(DirectiveAction, usize), String> = loop {
+      match dir_pointer {
+        CommandTree::Top(subcommands) | CommandTree::NonTerminal { children: subcommands, .. } => {
+          let next_command = match arguments.get(idx) {
+            Some(cmd) => cmd,
+            None => break Err(format!("Command requires arguments"))
+          };
+          idx += 1;
+          match subcommands.iter().find(|sc| sc.get_cmd() == *next_command) {
+            Some(command_tree) => {
+              dir_pointer = command_tree;
+            },
+            None => break Err(format!("Command {} not found", next_command))
+          };
+        },
+        CommandTree::Terminal { action, .. } => {
+          break Ok((action.clone(), idx));
+        },
+      }
+    };
+
+    match res {
+      Ok((action, idx)) => action.perform(repl, &arguments[idx..]),
+      Err(err) => Some(err.red().to_string())
     }
   }
 }

schala-repl/src/repl/directive_actions.rs

@@ -0,0 +1,133 @@
+use super::{Repl, InterpreterDirectiveOutput};
+use crate::repl::help::help;
+use crate::language::{LangMetaRequest, LangMetaResponse, DebugAsk, DebugResponse}; 
+use itertools::Itertools;
+use std::fmt::Write as FmtWrite;
+
+#[derive(Debug, Clone)]
+pub enum DirectiveAction {
+  Null,
+  Help,
+  QuitProgram,
+  ListPasses,
+  ShowImmediate,
+  Show,
+  Hide,
+  TotalTimeOff,
+  TotalTimeOn,
+  StageTimeOff,
+  StageTimeOn,
+  Doc,
+}
+
+impl DirectiveAction {
+  pub fn perform(&self, repl: &mut Repl, arguments: &[&str]) -> InterpreterDirectiveOutput {
+    use DirectiveAction::*;
+    match self {
+      Null => None,
+      Help => help(repl, arguments),
+      QuitProgram => {
+        repl.save_before_exit();
+        ::std::process::exit(0)
+      },
+      ListPasses => {
+        let language_state = repl.get_cur_language_state();
+        let pass_names = match language_state.request_meta(LangMetaRequest::StageNames) {
+          LangMetaResponse::StageNames(names) => names,
+          _ => vec![],
+        };
+
+        let mut buf = String::new();
+        for pass in pass_names.iter().map(|name| Some(name)).intersperse(None) {
+          match pass {
+            Some(pass) => write!(buf, "{}", pass).unwrap(),
+            None => write!(buf, " -> ").unwrap(),
+          }
+        }
+        Some(buf)
+      },
+      ShowImmediate => {
+        let cur_state = repl.get_cur_language_state();
+        let stage_name = match arguments.get(0) {
+          Some(s) => s.to_string(),
+          None => return Some(format!("Must specify a thing to debug")),
+        };
+        let meta = LangMetaRequest::ImmediateDebug(DebugAsk::ByStage { stage_name: stage_name.clone(), token: None });
+        let meta_response = cur_state.request_meta(meta);
+
+        let response = match meta_response {
+          LangMetaResponse::ImmediateDebug(DebugResponse { ask, value }) => match  ask {
+            DebugAsk::ByStage { stage_name: ref this_stage_name, ..} if *this_stage_name == stage_name => value,
+            _ => return Some(format!("Wrong debug stage"))
+          },
+          _ => return Some(format!("Invalid language meta response")),
+        };
+        Some(response)
+      },
+      Show => {
+        let this_stage_name = match arguments.get(0) {
+          Some(s) => s.to_string(),
+          None => return Some(format!("Must specify a stage to show")),
+        };
+        let token = arguments.get(1).map(|s| s.to_string());
+        repl.options.debug_asks.retain(|ask| match ask {
+          DebugAsk::ByStage { stage_name, .. } if *stage_name == this_stage_name => false,
+          _ => true
+        });
+
+        let ask = DebugAsk::ByStage { stage_name: this_stage_name, token };
+        repl.options.debug_asks.insert(ask);
+        None
+      },
+      Hide => {
+        let stage_name_to_remove = match arguments.get(0) {
+          Some(s) => s.to_string(),
+          None => return Some(format!("Must specify a stage to hide")),
+        };
+        repl.options.debug_asks.retain(|ask| match ask {
+          DebugAsk::ByStage { stage_name, .. } if *stage_name == stage_name_to_remove => false,
+          _ => true
+        });
+        None
+      },
+      TotalTimeOff => total_time_off(repl, arguments),
+      TotalTimeOn => total_time_on(repl, arguments),
+      StageTimeOff => stage_time_off(repl, arguments),
+      StageTimeOn => stage_time_on(repl, arguments),
+      Doc => doc(repl, arguments),
+    }
+  }
+}
+
+fn total_time_on(repl: &mut Repl, _: &[&str]) -> InterpreterDirectiveOutput {
+  repl.options.show_total_time = true;
+  None
+}
+
+fn total_time_off(repl: &mut Repl, _: &[&str]) -> InterpreterDirectiveOutput {
+  repl.options.show_total_time = false;
+  None
+}
+
+fn stage_time_on(repl: &mut Repl, _: &[&str]) -> InterpreterDirectiveOutput {
+  repl.options.show_stage_times = true;
+  None
+}
+
+fn stage_time_off(repl: &mut Repl, _: &[&str]) -> InterpreterDirectiveOutput {
+  repl.options.show_stage_times = false;
+  None
+}
+
+fn doc(repl: &mut Repl, arguments: &[&str]) -> InterpreterDirectiveOutput {
+  arguments.get(0).map(|cmd| {
+    let source = cmd.to_string();
+    let meta = LangMetaRequest::Docs { source };
+    let cur_state = repl.get_cur_language_state();
+    match cur_state.request_meta(meta) {
+      LangMetaResponse::Docs { doc_string } => Some(doc_string),
+      _ => Some(format!("Invalid doc response"))
+    }
+  }).unwrap_or(Some(format!(":docs needs an argument")))
+}
+

schala-repl/src/repl/directives.rs

@@ -0,0 +1,55 @@
+use crate::repl::command_tree::CommandTree;
+use crate::repl::directive_actions::DirectiveAction;
+
+pub fn directives_from_pass_names(pass_names: &Vec<String>) -> CommandTree {
+  let passes_directives: Vec<CommandTree> = pass_names.iter()
+    .map(|pass_name| {
+      if pass_name == "parsing" {
+        CommandTree::nonterm(pass_name, None, vec![
+          CommandTree::nonterm_no_further_tab_completions("compact", None),
+          CommandTree::nonterm_no_further_tab_completions("expanded", None),
+          CommandTree::nonterm_no_further_tab_completions("trace", None),
+        ])
+      } else {
+        CommandTree::nonterm_no_further_tab_completions(pass_name, None) 
+      }
+    })
+    .collect();
+  CommandTree::Top(get_list(&passes_directives, true))
+}
+
+fn get_list(passes_directives: &Vec<CommandTree>, include_help: bool) -> Vec<CommandTree> {
+  use DirectiveAction::*;
+
+  vec![
+    CommandTree::terminal("exit", Some("exit the REPL"), vec![], QuitProgram),
+    CommandTree::terminal("quit", Some("exit the REPL"), vec![], QuitProgram),
+    CommandTree::terminal("help", Some("Print this help message"), if include_help { get_list(passes_directives, false) } else { vec![] }, Help),
+    CommandTree::nonterm("debug",
+      Some("Configure debug information"),
+      vec![
+        CommandTree::terminal("list-passes", Some("List all registered compiler passes"), vec![], ListPasses),
+        CommandTree::terminal("show-immediate", None, passes_directives.clone(), ShowImmediate),
+        CommandTree::terminal("show", Some("Show debug output for a specific pass"), passes_directives.clone(), Show),
+        CommandTree::terminal("hide", Some("Hide debug output for a specific pass"), passes_directives.clone(), Hide),
+        CommandTree::nonterm("total-time", None, vec![
+          CommandTree::terminal("on", None, vec![], TotalTimeOn), 
+          CommandTree::terminal("off", None, vec![], TotalTimeOff),
+        ]),
+        CommandTree::nonterm("stage-times", Some("Computation time per-stage"), vec![
+          CommandTree::terminal("on", None, vec![], StageTimeOn),
+          CommandTree::terminal("off", None, vec![], StageTimeOff),
+        ])
+      ]
+    ),
+    CommandTree::nonterm("lang",
+      Some("switch between languages, or go directly to a langauge by name"),
+      vec![
+        CommandTree::nonterm_no_further_tab_completions("next", None),
+        CommandTree::nonterm_no_further_tab_completions("prev", None),
+        CommandTree::nonterm("go", None, vec![]),
+      ]
+    ),
+    CommandTree::terminal("doc", Some("Get language-specific help for an item"), vec![], Doc),
+  ]
+}

schala-repl/src/repl/help.rs

@@ -0,0 +1,54 @@
+use std::fmt::Write as FmtWrite;
+
+use colored::*;
+use super::command_tree::CommandTree;
+use super::{Repl, InterpreterDirectiveOutput};
+
+pub fn help(repl: &mut Repl, arguments: &[&str]) -> InterpreterDirectiveOutput {
+  match arguments {
+    [] =>  return global_help(repl),
+    commands => {
+      let dirs = repl.get_directives();
+      Some(match get_directive_from_commands(commands, &dirs) {
+        None => format!("Directive `{}` not found", commands.last().unwrap()),
+        Some(dir) => {
+          let mut buf = String::new();
+          writeln!(buf, "`{}` - {}", dir.get_cmd(), dir.get_help()).unwrap();
+          buf
+        }
+      })
+    }
+  }
+}
+
+fn get_directive_from_commands<'a>(commands: &[&str], dirs: &'a CommandTree) -> Option<&'a CommandTree> {
+  let mut directive_list = dirs.get_children();
+  let mut matched_directive = None;
+  for cmd in commands {
+    let found = directive_list.iter().find(|directive| directive.get_cmd() == *cmd);
+    if let Some(dir) = found {
+      directive_list = dir.get_children();
+    }
+
+    matched_directive = found;
+  }
+  matched_directive
+}
+
+fn global_help(repl: &mut Repl) -> InterpreterDirectiveOutput {
+  let mut buf = String::new();
+  let sigil = repl.interpreter_directive_sigil;
+
+  writeln!(buf, "{} version {}", "Schala REPL".bright_red().bold(), crate::VERSION_STRING).unwrap();
+  writeln!(buf, "-----------------------").unwrap();
+
+  for directive in repl.get_directives().get_children() {
+    writeln!(buf, "{}{} - {}", sigil, directive.get_cmd(), directive.get_help()).unwrap();
+  }
+
+  let ref lang = repl.get_cur_language_state();
+  writeln!(buf, "").unwrap();
+  writeln!(buf, "Language-specific help for {}", lang.get_language_name()).unwrap();
+  writeln!(buf, "-----------------------").unwrap();
+  Some(buf)
+}

schala-repl/src/repl/mod.rs

@@ -1,297 +1,151 @@
-use std::fmt::Write as FmtWrite;
-use std::io::{Read, Write};
-use std::fs::File;
 use std::sync::Arc;
+use std::collections::HashSet;
+
+use crate::language::{ProgrammingLanguageInterface,
+ComputationRequest, LangMetaResponse, LangMetaRequest};
 
-use colored::*;
-use itertools::Itertools;
-use language::{ProgrammingLanguageInterface, EvalOptions,
-  PassDebugOptionsDescriptor};
 mod command_tree;
 use self::command_tree::CommandTree;
+mod repl_options;
+use repl_options::ReplOptions;
+mod directive_actions;
+mod directives;
+use directives::directives_from_pass_names;
+mod help;
+mod response;
+use response::ReplResponse;
 
 const HISTORY_SAVE_FILE: &'static str = ".schala_history";
 const OPTIONS_SAVE_FILE: &'static str = ".schala_repl";
 
+type InterpreterDirectiveOutput = Option<String>;
+
 pub struct Repl {
-  options: EvalOptions,
-  languages: Vec<Box<ProgrammingLanguageInterface>>,
-  current_language_index: usize,
-  interpreter_directive_sigil: char,
+  pub interpreter_directive_sigil: char,
   line_reader: ::linefeed::interface::Interface<::linefeed::terminal::DefaultTerminal>,
+  language_states: Vec<Box<dyn ProgrammingLanguageInterface>>,
+  options: ReplOptions,
 }
 
 impl Repl {
-  pub fn new(languages: Vec<Box<ProgrammingLanguageInterface>>, initial_index: usize) -> Repl {
+  pub fn new(initial_states: Vec<Box<dyn ProgrammingLanguageInterface>>) -> Repl {
     use linefeed::Interface;
-    let current_language_index = if initial_index < languages.len() { initial_index } else { 0 };
-
     let line_reader = Interface::new("schala-repl").unwrap();
+    let interpreter_directive_sigil = ':';
 
     Repl {
-      options: Repl::get_options(),
-      languages,
-      current_language_index,
-      interpreter_directive_sigil: ':',
-      line_reader
+      interpreter_directive_sigil,
+      line_reader,
+      language_states: initial_states,
+      options: ReplOptions::new(),
     }
   }
 
-  fn get_cur_language(&self) -> &ProgrammingLanguageInterface {
-    self.languages[self.current_language_index].as_ref()
-  }
-
-  fn get_options() -> EvalOptions {
-    File::open(OPTIONS_SAVE_FILE)
-      .and_then(|mut file| {
-        let mut contents = String::new();
-        file.read_to_string(&mut contents)?;
-        Ok(contents)
-      })
-      .and_then(|contents| {
-        let options: EvalOptions = ::serde_json::from_str(&contents)?;
-        Ok(options)
-      }).unwrap_or(EvalOptions::default())
-  }
-
-  fn save_options(&self) {
-    let ref options = self.options;
-    let read = File::create(OPTIONS_SAVE_FILE)
-      .and_then(|mut file| {
-        let buf = ::serde_json::to_string(options).unwrap();
-        file.write_all(buf.as_bytes())
-      });
-
-    if let Err(err) = read {
-      println!("Error saving {} file {}", OPTIONS_SAVE_FILE, err);
-    }
-  }
-
-  pub fn run(&mut self) {
-    use linefeed::ReadResult;
-
-    println!("Schala MetaInterpreter version {}", ::VERSION_STRING);
+  pub fn run_repl(&mut self) {
+    println!("Schala MetaInterpreter version {}", crate::VERSION_STRING);
     println!("Type {}help for help with the REPL", self.interpreter_directive_sigil);
+    self.load_options();
+    self.handle_repl_loop();
+    self.save_before_exit();
+    println!("Exiting...");
+  }
 
+  fn load_options(&mut self) {
     self.line_reader.load_history(HISTORY_SAVE_FILE).unwrap_or(());
+    match ReplOptions::load_from_file(OPTIONS_SAVE_FILE) {
+      Ok(options) => {
+        self.options = options;
+      },
+      Err(()) => ()
+    };
+  }
+
+  fn handle_repl_loop(&mut self) {
+    use linefeed::ReadResult::*;
 
     loop {
-      let language_name = self.get_cur_language().get_language_name();
-      let directives = self.get_directives();
-      let tab_complete_handler = TabCompleteHandler::new(self.interpreter_directive_sigil, directives);
-      self.line_reader.set_completer(Arc::new(tab_complete_handler));
-
-      let prompt_str = format!("{} >> ", language_name);
-      self.line_reader.set_prompt(&prompt_str).unwrap();
-
+      self.update_line_reader();
       match self.line_reader.read_line() {
         Err(e) => {
-          println!("Terminal read error: {}", e);
+          println!("readline IO Error: {}", e);
+          break;
         },
-        Ok(ReadResult::Eof) => break,
-        Ok(ReadResult::Signal(_)) => break,
-        Ok(ReadResult::Input(ref input)) => {
+        Ok(Eof) | Ok(Signal(_)) => break,
+        Ok(Input(ref input)) => {
           self.line_reader.add_history_unique(input.to_string());
-          let output = match input.chars().nth(0) {
-            Some(ch) if ch == self.interpreter_directive_sigil => self.handle_interpreter_directive(input),
-            _ => Some(self.input_handler(input)),
-          };
-          if let Some(o) = output {
-            println!("=> {}", o);
+          match input.chars().nth(0) {
+            Some(ch) if ch == self.interpreter_directive_sigil => match self.handle_interpreter_directive(input) {
+              Some(directive_output) => println!("<> {}", directive_output),
+              None => (),
+            },
+            _ => {
+              for repl_response in self.handle_input(input) {
+                println!("{}", repl_response);
+              }
+            }
           }
         }
       }
     }
+  }
+
+  fn update_line_reader(&mut self) {
+    let tab_complete_handler = TabCompleteHandler::new(self.interpreter_directive_sigil, self.get_directives());
+    self.line_reader.set_completer(Arc::new(tab_complete_handler)); //TODO fix this here
+    let prompt_str = format!(">> ");
+    self.line_reader.set_prompt(&prompt_str).unwrap();
+  }
+
+  fn save_before_exit(&self) {
     self.line_reader.save_history(HISTORY_SAVE_FILE).unwrap_or(());
-    self.save_options();
-    println!("Exiting...");
+    self.options.save_to_file(OPTIONS_SAVE_FILE);
   }
 
-  fn input_handler(&mut self, input: &str) -> String {
-    let ref mut language = self.languages[self.current_language_index];
-    let interpreter_output = language.execute_pipeline(input, &self.options);
-    interpreter_output.to_repl()
-  }
-
-  fn get_directives(&self) -> CommandTree {
-    let ref passes = self.get_cur_language().get_passes();
-
-    let passes_directives: Vec<CommandTree> = passes.iter()
-      .map(|pass_descriptor| {
-        let name = &pass_descriptor.name;
-        if pass_descriptor.debug_options.len() == 0 {
-          CommandTree::term(name, None)
-        } else {
-          let children: Vec<CommandTree> = pass_descriptor.debug_options.iter()
-            .map(|o| CommandTree::term(o, None)).collect();
-          CommandTree::NonTerminal {
-            name: name.clone(),
-            children,
-            help_msg: None,
-            function: None,
-          }
-        }
-      }).collect();
-
-    CommandTree::Top(vec![
-      CommandTree::term("exit", Some("exit the REPL")),
-      CommandTree::term("quit", Some("exit the REPL")),
-      CommandTree::term("help", Some("Print this help message")),
-      CommandTree::nonterm("debug",
-        Some("show or hide pass debug info for a given pass, or display the names of all passes, or turn timing on/off"),
-        vec![
-          CommandTree::term("passes", None),
-          CommandTree::nonterm("show", None, passes_directives.clone()),
-          CommandTree::nonterm("hide", None, passes_directives.clone()),
-          CommandTree::nonterm("timing", None, vec![
-            CommandTree::term("on", None),
-            CommandTree::term("off", None),
-          ])
-        ]
-      ),
-      CommandTree::nonterm("lang",
-        Some("switch between languages, or go directly to a langauge by name"),
-        vec![
-          CommandTree::term("next", None),
-          CommandTree::term("prev", None),
-          CommandTree::nonterm("go", None, vec![]),
-        ]
-      ),
-      CommandTree::term("doc", Some("Get language-specific help for an item")),
-    ])
-  }
-
-  fn handle_interpreter_directive(&mut self, input: &str) -> Option<String> {
+  fn handle_interpreter_directive(&mut self, input: &str) -> InterpreterDirectiveOutput {
     let mut iter = input.chars();
     iter.next();
-    let commands: Vec<&str> = iter
+    let arguments: Vec<&str> = iter
       .as_str()
       .split_whitespace()
       .collect();
 
-    let initial_cmd: &str = match commands.get(0).clone() {
-      None => return None,
-      Some(s) => s
+    if arguments.len() < 1 {
+      return None;
+    }
+
+    let directives = self.get_directives();
+    directives.perform(self, &arguments)
+  }
+
+  fn get_cur_language_state(&mut self) -> &mut Box<dyn ProgrammingLanguageInterface> {
+    //TODO this is obviously not complete
+    &mut self.language_states[0]
+  }
+
+  fn handle_input(&mut self, input: &str) -> Vec<ReplResponse> {
+    let mut debug_requests = HashSet::new();
+    for ask in self.options.debug_asks.iter() {
+      debug_requests.insert(ask.clone());
+    }
+
+    let request = ComputationRequest { source: input, debug_requests };
+    let ref mut language_state = self.get_cur_language_state();
+    let response = language_state.run_computation(request);
+    response::handle_computation_response(response, &self.options)
+  }
+
+  fn get_directives(&mut self) -> CommandTree {
+    let language_state = self.get_cur_language_state();
+    let pass_names = match language_state.request_meta(LangMetaRequest::StageNames) {
+      LangMetaResponse::StageNames(names) => names,
+      _ => vec![],
     };
 
-    match initial_cmd {
-      "exit" | "quit"  => {
-        self.save_options();
-        ::std::process::exit(0)
-      },
-      "lang" | "language" => match commands.get(1) {
-        Some(&"show") => {
-          let mut buf = String::new();
-          for (i, lang) in self.languages.iter().enumerate() {
-            write!(buf, "{}{}\n", if i == self.current_language_index { "* "} else { "" }, lang.get_language_name()).unwrap();
-          }
-          Some(buf)
-        },
-        Some(&"go") => match commands.get(2) {
-          None => Some(format!("Must specify a language name")),
-          Some(&desired_name) => {
-            for (i, _) in self.languages.iter().enumerate() {
-              let lang_name = self.languages[i].get_language_name();
-              if lang_name.to_lowercase() == desired_name.to_lowercase() {
-                self.current_language_index = i;
-                return Some(format!("Switching to {}", self.languages[self.current_language_index].get_language_name()));
-              }
-            }
-            Some(format!("Language {} not found", desired_name))
-          }
-        },
-        Some(&"next") | Some(&"n") => {
-          self.current_language_index = (self.current_language_index + 1) % self.languages.len();
-          Some(format!("Switching to {}", self.languages[self.current_language_index].get_language_name()))
-        },
-        Some(&"previous") | Some(&"p") | Some(&"prev") => { 
-          self.current_language_index = if self.current_language_index == 0 { self.languages.len() - 1 } else { self.current_language_index - 1 };
-          Some(format!("Switching to {}", self.languages[self.current_language_index].get_language_name()))
-        },
-        Some(e) => Some(format!("Bad `lang(uage)` argument: {}", e)),
-        None => Some(format!("Valid arguments for `lang(uage)` are `show`, `next`|`n`, `previous`|`prev`|`n`"))
-      },
-      "help" =>  {
-        let mut buf = String::new();
-        let ref lang = self.languages[self.current_language_index];
-        let directives = match self.get_directives() {
-            CommandTree::Top(children) => children,
-            _ => panic!("Top-level CommandTree not Top")
-        };
-
-        writeln!(buf, "MetaInterpreter options").unwrap();
-        writeln!(buf, "-----------------------").unwrap();
-
-        for directive in directives {
-          let trailer = " ";
-          writeln!(buf, "{}{}- {}", directive.get_cmd(), trailer, directive.get_help()).unwrap();
-        }
-
-        writeln!(buf, "").unwrap();
-        writeln!(buf, "Language-specific help for {}", lang.get_language_name()).unwrap();
-        writeln!(buf, "-----------------------").unwrap();
-        writeln!(buf, "{}", lang.custom_interpreter_directives_help()).unwrap();
-        Some(buf)
-      },
-      "debug" => self.handle_debug(commands),
-      "doc" => self.languages[self.current_language_index]
-        .get_doc(&commands)
-        .or(Some(format!("No docs implemented"))),
-      e => {
-        self.languages[self.current_language_index]
-        .handle_custom_interpreter_directives(&commands)
-        .or(Some(format!("Unknown command: {}", e)))
-      }
-    }
-  }
-  fn handle_debug(&mut self, commands: Vec<&str>) -> Option<String> {
-    let passes = self.get_cur_language().get_passes();
-    match commands.get(1) {
-      Some(&"timing") => match commands.get(2) {
-        Some(&"on") => { self.options.debug_timing = true; None }
-        Some(&"off") => { self.options.debug_timing = false; None }
-        _ => return Some(format!(r#"Argument to "timing" must be "on" or "off""#)),
-      },
-      Some(&"passes") => Some(
-        passes.into_iter()
-        .map(|desc| {
-          if self.options.debug_passes.contains_key(&desc.name) {
-            let color = "green";
-            format!("*{}", desc.name.color(color))
-          } else {
-            desc.name
-          }
-        })
-        .intersperse(format!(" -> "))
-        .collect()),
-      b @ Some(&"show") | b @ Some(&"hide") => {
-        let show = b == Some(&"show");
-        let debug_pass: String = match commands.get(2) {
-          Some(s) => s.to_string(),
-          None => return Some(format!("Must specify a stage to debug")),
-        };
-        let pass_opt = commands.get(3);
-        if let Some(desc) = passes.iter().find(|desc| desc.name == debug_pass) {
-          let mut opts = vec![];
-          if let Some(opt) = pass_opt {
-            opts.push(opt.to_string());
-          }
-          let msg = format!("{} debug for pass {}", if show { "Enabling" } else { "Disabling" }, debug_pass);
-          if show {
-            self.options.debug_passes.insert(desc.name.clone(), PassDebugOptionsDescriptor { opts });
-          } else {
-            self.options.debug_passes.remove(&desc.name);
-          }
-          Some(msg)
-        } else {
-          Some(format!("Couldn't find stage: {}", debug_pass))
-        }
-      },
-      _ => Some(format!("Unknown debug command"))
-    }
+    directives_from_pass_names(&pass_names)
   }
 }
 
+
 struct TabCompleteHandler {
   sigil: char,
   top_level_commands: CommandTree,
@@ -313,43 +167,43 @@ impl<T: Terminal> Completer<T> for TabCompleteHandler {
   fn complete(&self, word: &str, prompter: &::linefeed::prompter::Prompter<T>, start: usize, _end: usize) -> Option<Vec<Completion>> {
     let line = prompter.buffer();
 
-    if line.starts_with(&format!("{}", self.sigil)) {
-      let mut words = line[1..(if start == 0 { 1 } else { start })].split_whitespace();
-      let mut completions = Vec::new();
-      let mut command_tree: Option<&CommandTree> = Some(&self.top_level_commands);
+    if !line.starts_with(self.sigil) {
+      return None;
+    }
 
-      loop {
-        match words.next() {
-          None => {
-            let top = match command_tree {
-              Some(CommandTree::Top(_)) => true,
-              _ => false
-            };
-            let word = if top { word.get(1..).unwrap() } else { word };
-            for cmd in command_tree.map(|x| x.get_children()).unwrap_or(vec![]).into_iter() {
-              if cmd.starts_with(word) {
-                completions.push(Completion {
-                    completion: format!("{}{}", if top { ":" } else { "" }, cmd),
-                    display: Some(cmd.to_string()),
-                    suffix: ::linefeed::complete::Suffix::Some(' ')
-                })
-              }
+    let mut words = line[1..(if start == 0 { 1 } else { start })].split_whitespace();
+    let mut completions = Vec::new();
+    let mut command_tree: Option<&CommandTree> = Some(&self.top_level_commands);
+
+    loop {
+      match words.next() {
+        None => {
+          let top = match command_tree {
+            Some(CommandTree::Top(_)) => true,
+            _ => false
+          };
+          let word = if top { word.get(1..).unwrap() } else { word };
+          for cmd in command_tree.map(|x| x.get_subcommands()).unwrap_or(vec![]).into_iter() {
+            if cmd.starts_with(word) {
+              completions.push(Completion {
+                completion: format!("{}{}", if top { ":" } else { "" }, cmd),
+                display: Some(cmd.to_string()),
+                suffix: ::linefeed::complete::Suffix::Some(' ')
+              })
             }
-            break;
-          },
-          Some(s) => {
-            let new_ptr: Option<&CommandTree> = command_tree.and_then(|cm| match cm {
-              CommandTree::Top(children) => children.iter().find(|c| c.get_cmd() == s),
-              CommandTree::NonTerminal { children, .. } => children.iter().find(|c| c.get_cmd() == s),
-              CommandTree::Terminal { .. } => None,
-            });
-            command_tree = new_ptr;
           }
+          break;
+        },
+        Some(s) => {
+          let new_ptr: Option<&CommandTree> = command_tree.and_then(|cm| match cm {
+            CommandTree::Top(children) => children.iter().find(|c| c.get_cmd() == s),
+            CommandTree::NonTerminal { children, .. } => children.iter().find(|c| c.get_cmd() == s),
+            CommandTree::Terminal { children, .. } => children.iter().find(|c| c.get_cmd() == s),
+          });
+          command_tree = new_ptr;
         }
       }
-      Some(completions)
-    } else {
-      None
     }
+    Some(completions)
   }
 }

schala-repl/src/repl/repl_options.rs

@@ -0,0 +1,47 @@
+use crate::language::DebugAsk;
+
+use std::io::{Read, Write};
+use std::collections::HashSet;
+use std::fs::File;
+
+#[derive(Serialize, Deserialize)]
+pub struct ReplOptions {
+  pub debug_asks: HashSet<DebugAsk>,
+  pub show_total_time: bool,
+  pub show_stage_times: bool,
+}
+
+impl ReplOptions {
+  pub fn new() -> ReplOptions {
+    ReplOptions {
+      debug_asks: HashSet::new(),
+      show_total_time: true,
+      show_stage_times: false,
+    }
+  }
+
+  pub fn save_to_file(&self, filename: &str) {
+    let res = File::create(filename)
+      .and_then(|mut file| {
+        let buf = crate::serde_json::to_string(self).unwrap();
+        file.write_all(buf.as_bytes())
+      });
+    if let Err(err) = res {
+      println!("Error saving {} file {}", filename, err);
+    }
+  }
+
+  pub fn load_from_file(filename: &str) -> Result<ReplOptions, ()> {
+    File::open(filename)
+      .and_then(|mut file| {
+        let mut contents = String::new();
+        file.read_to_string(&mut contents)?;
+        Ok(contents)
+      })
+    .and_then(|contents| {
+      let output: ReplOptions = crate::serde_json::from_str(&contents)?;
+      Ok(output)
+    })
+    .map_err(|_| ())
+  }
+}

schala-repl/src/repl/response.rs

@@ -0,0 +1,67 @@
+use colored::*;
+use std::fmt;
+use std::fmt::Write;
+
+use super::ReplOptions;
+use crate::language::{ DebugAsk, ComputationResponse};
+
+pub struct ReplResponse {
+  label: Option<String>,
+  text: String,
+  color: Option<Color>
+}
+
+impl fmt::Display for ReplResponse {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    let mut buf = String::new();
+    if let Some(ref label) = self.label {
+      write!(buf, "({})", label).unwrap();
+    }
+    write!(buf, "=> {}", self.text).unwrap();
+    write!(f, "{}", match self.color {
+      Some(c) => buf.color(c),
+      None => buf.normal()
+    })
+  }
+}
+
+
+pub fn handle_computation_response(response: ComputationResponse, options: &ReplOptions) -> Vec<ReplResponse> {
+  let mut responses = vec![];
+
+  if options.show_total_time {
+    responses.push(ReplResponse {
+      label: Some("Total time".to_string()),
+      text: format!("{:?}", response.global_output_stats.total_duration),
+      color: None,
+    });
+  }
+
+  if options.show_stage_times {
+    responses.push(ReplResponse {
+      label: Some("Stage times".to_string()),
+      text: format!("{:?}", response.global_output_stats.stage_durations),
+      color: None,
+    });
+  }
+
+  for debug_resp in response.debug_responses {
+    let stage_name = match debug_resp.ask {
+      DebugAsk::ByStage { stage_name, .. } => stage_name,
+      _ => continue,
+    };
+    responses.push(ReplResponse {
+      label: Some(stage_name.to_string()),
+      text: debug_resp.value,
+      color: Some(Color::Red),
+    });
+  }
+
+  responses.push(match response.main_output {
+    Ok(s) => ReplResponse { label: None, text: s, color: None },
+    Err(e) => ReplResponse { label: Some("Error".to_string()), text: e, color: Some(Color::Red) },
+  });
+
+  responses
+}
+

schala-repl/src/webapp.rs

@@ -1,44 +0,0 @@
-use rocket;
-use rocket::State;
-use rocket::response::Content;
-use rocket::http::ContentType;
-use rocket_contrib::json::Json;
-use language::{ProgrammingLanguageInterface, EvalOptions};
-use WEBFILES;
-use ::PLIGenerator;
-
-#[get("/")]
-fn index() -> Content<String> {
-  let path = "static/index.html";
-  let html_contents = String::from_utf8(WEBFILES.get(path).unwrap().into_owned()).unwrap();
-  Content(ContentType::HTML, html_contents)
-}
-
-#[get("/bundle.js")]
-fn js_bundle() -> Content<String> {
-  let path = "static/bundle.js";
-  let js_contents = String::from_utf8(WEBFILES.get(path).unwrap().into_owned()).unwrap();
-  Content(ContentType::JavaScript, js_contents)
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-struct Input {
-  source: String,
-}
-
-#[derive(Serialize, Deserialize)]
-struct Output {
-  text: String,
-}
-
-#[post("/input", format = "application/json", data = "<input>")]
-fn interpreter_input(input: Json<Input>, generators: State<Vec<PLIGenerator>>) -> Json<Output> {
-  let schala_gen = generators.get(0).unwrap();
-  let mut schala: Box<ProgrammingLanguageInterface> = schala_gen();
-  let code_output = schala.execute_pipeline(&input.source, &EvalOptions::default());
-  Json(Output { text: code_output.to_repl() })
-}
-
-pub fn web_main(language_generators: Vec<PLIGenerator>) {
-  rocket::ignite().manage(language_generators).mount("/", routes![index, js_bundle, interpreter_input]).launch();
-}

src/main.rs

@@ -1,20 +1,15 @@
 extern crate schala_repl;
 
-extern crate maaru_lang;
-extern crate rukka_lang;
-extern crate robo_lang;
+//extern crate maaru_lang;
+//extern crate rukka_lang;
+//extern crate robo_lang;
 extern crate schala_lang;
-use schala_repl::{PLIGenerator, repl_main};
+use schala_repl::{ProgrammingLanguageInterface, start_repl};
 
 extern { }
 
 fn main() {
-  let generators: Vec<PLIGenerator> = vec![
-    Box::new(|| { Box::new(schala_lang::Schala::new())}),
-    Box::new(|| { Box::new(maaru_lang::Maaru::new())}),
-    Box::new(|| { Box::new(robo_lang::Robo::new())}),
-    Box::new(|| { Box::new(rukka_lang::Rukka::new())}),
-  ];
-  repl_main(generators);
+  let langs: Vec<Box<dyn ProgrammingLanguageInterface>> = vec![Box::new(schala_lang::Schala::new())];
+  start_repl(langs);
 }