Move stuff around

WIP

.gitignore

@@ -2,3 +2,4 @@ Cargo.lock
 target
 .schala_repl
 .schala_history
+rusty-tags.vi

Cargo.toml

@@ -6,11 +6,12 @@ authors = ["greg <greg.shuflin@protonmail.com>"]
 [dependencies]
 
 schala-repl = { path = "schala-repl" }
-schala-codegen = { path = "schala-codegen" }
+schala-repl-codegen = { path = "schala-repl-codegen" }
 maaru-lang = { path = "maaru" }
 rukka-lang = { path = "rukka" }
 robo-lang = { path = "robo" }
-schala-lang = { path = "schala-lang" }
+schala-lang = { path = "schala-lang/language" }
+schala-lang-codegen = { path = "schala-lang/codegen" }
 
 [build-dependencies]
 includedir_codegen = "0.2.0"

Grammar

@@ -1,31 +0,0 @@
-
-
-<program> := <statements> EOF
-
-<statements> := <statement>
-             |  <statement> SEP <statements>
-
-<statement> := let <id> = <expr>
-            |  <expr>
-            | <fn_block>
-
-<fn_block> := fn <id> ( <arg_list> ) <statements> end
-
-<arg_list> := e
-           | <id>
-           | <id> , <arg_list>
-
-<expr> := if <expr> then <statements> end
-       |  if <expr> then <statements> else <statements> end
-       |  while <expr> SEP <statements> end
-       |  ( <expr> )
-       |  <binop>
-
-<binop> := <simple_expr>
-        |  <simple_expr> <id> <binop>
-
-<simple_expr> := <id>
-              | <number>
-              | <string>
-
-

README.md

@@ -1,21 +1,21 @@
-
 # 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 common REPL, and a trait `ProgrammingLanguage` with provisions
-for tokenizing text, parsing tokens, evaluating an abstract syntax tree,
-and other tasks that are common to all programming languages.
+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
+provisions for tokenizing text, parsing tokens, evaluating an abstract syntax
+tree, and other tasks that are common to all programming languages.
 
-Schala is implemented as a Rust library `schala_lib`, which provides a
-`schala_main` function. This function serves as the main loop of the REPL, if run
-interactively, or otherwise reads and interprets programming language source
-files. It expects as input a vector of `PLIGenerator`, which is a type representing
-a closure that returns a boxed trait object that implements the `ProgrammingLanguage` trait,
-and stores any persistent state relevant to that programming language. The ability
-to share state between different programming languages is in the works.
+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.
 
-## About
+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.
+
+## History
 
 Schala started out life as an experiment in writing a Javascript-like
 programming language that would never encounter any kind of runtime value
@@ -58,6 +58,9 @@ of learning how to write a programming language.
 
 ### 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
 
 ### Evaluation
 *Understanding Computation*, Tom Stuart, O'Reilly 2013
@@ -67,6 +70,7 @@ https://skillsmatter.com/skillscasts/10868-inside-the-rust-compiler
 ### Parsing
 http://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/
 https://soc.github.io/languages/unified-condition-syntax
+http://www.lihaoyi.com/post/ZeroOverheadTreeProcessingwiththeVisitorPattern.html?a=1
 
 [Crafting Interpreters](http://www.craftinginterpreters.com/)
 
@@ -75,4 +79,5 @@ http://blog.ulysse.io/2016/07/03/llvm-getting-started.html
 
 ###Rust resources
 https://thefullsnack.com/en/rust-for-the-web.html
+
 https://rocket.rs/guide/getting-started/

TODO.md

@@ -1,6 +1,26 @@
 
 # TODO Items
 
+-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
+
+- 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
+
+-scala-style html"dfasfsadf${}" string interpolations!
+
+-fuzz test schala
+
+
+*A neat idea for pattern matching optimization would be if you could match on one of several things in a list
+ex:
+if x {
+ is (comp, LHSPat, RHSPat) if comp in ["==, "<"] -> ...
+}
+
 
 - https://nshipster.com/never/
 -https://cranelift.readthedocs.io/en/latest/?badge=latest<Paste>
@@ -94,10 +114,7 @@ type enum {
 
 
 
-- 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
 
--scala-style html"dfasfsadf${}" string interpolations!
 
 *Compiler passes architecture
 

schala-codegen/src/lib.rs

@@ -1,103 +0,0 @@
-#![feature(trace_macros)]
-#![feature(proc_macro)]
-extern crate proc_macro;
-#[macro_use]
-extern crate quote;
-extern crate syn;
-
-extern crate schala_repl;
-
-use proc_macro::TokenStream;
-use syn::{Ident, Attribute, DeriveInput};
-
-fn extract_attribute_arg_by_name(name: &str, attrs: &Vec<Attribute>) -> Option<String> {
-  use syn::{Meta, Lit, MetaNameValue};
-  attrs.iter().map(|attr| attr.interpret_meta()).find(|meta| {
-    match meta {
-      &Some(Meta::NameValue(MetaNameValue { ident, .. })) if ident.as_ref() == name => true,
-      _ => false
-    }
-  }).and_then(|meta| {
-    match 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};
-  attrs.iter().find(|attr| {
-    match attr.path.segments.iter().nth(0) {
-      Some(segment) if segment.ident.as_ref() == name => true,
-      _ => false
-    }
-  }).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(ident)) => (ident, None),
-          &NestedMeta::Meta(Meta::List(MetaList { ident, nested: ref nested2, .. })) => {
-            let own_args = nested2.iter().map(|nested_meta2| match nested_meta2 {
-              &NestedMeta::Meta(Meta::Word(ident)) => ident,
-              _ => panic!("Bad format for doubly-nested attribute list")
-            }).collect();
-            (ident, Some(own_args))
-          },
-          _ => panic!("Bad format for nested list")
-        }).collect())
-      },
-      _ => panic!("{} must be a comma-delimited list surrounded by parens", name)
-    }
-  })
-}
-
-#[proc_macro_derive(ProgrammingLanguageInterface, attributes(LanguageName, SourceFileExtension, PipelineSteps))]
-pub fn derive_programming_language_interface(input: TokenStream) -> TokenStream {
-  use schala_repl::PassDescriptor;
-  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);
-
-  //let pass_names: Vec<String> = passes.iter().map(|pass| pass.0.to_string()).collect();
-  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 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 {
-        let mut chain = pass_chain![self, options; #(#pass_idents),* ];
-        chain(input)
-      }
-      fn get_passes(&self) -> Vec<PassDescriptor> {
-        vec![ #(#pass_descriptors),* ]
-        //vec![ #(PassDescriptor { name: #pass_names.to_string(), debug_options: vec![] }),* ]
-      }
-    }
-  };
-  tokens.into()
-}

schala-lang/codegen/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "schala-lang-codegen"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+edition = "2018"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = { version = "0.15.12", features = ["full", "extra-traits", "fold"] }
+quote = "0.6.8"

schala-lang/codegen/src/lib.rs

@@ -0,0 +1,54 @@
+#![feature(box_patterns)]
+#![recursion_limit="128"]
+extern crate proc_macro;
+#[macro_use]
+extern crate quote;
+#[macro_use]
+extern crate syn;
+
+use self::proc_macro::TokenStream;
+use self::syn::fold::Fold;
+
+struct RecursiveDescentFn {
+}
+
+impl Fold for RecursiveDescentFn {
+  fn fold_item_fn(&mut self, mut i: syn::ItemFn) -> syn::ItemFn {
+    let box block = i.block;
+    let ref ident = i.ident;
+
+    let new_block: syn::Block = parse_quote! {
+      {
+        let next_token = self.peek_with_token_offset();
+        let record = ParseRecord {
+          production_name: stringify!(#ident).to_string(),
+          next_token: format!("{}", next_token.to_string_with_metadata()),
+          level: self.parse_level,
+        };
+        self.parse_level += 1;
+        self.parse_record.push(record);
+        let result = { #block };
+
+        if self.parse_level != 0 {
+          self.parse_level -= 1;
+        }
+        match result {
+          Err(ParseError { token: None, msg }) =>
+            Err(ParseError { token: Some(next_token), msg }),
+          _ => result
+        }
+      }
+    };
+    i.block = Box::new(new_block);
+    i
+  }
+}
+
+#[proc_macro_attribute]
+pub fn recursive_descent_method(_attr: TokenStream, item: TokenStream) -> TokenStream {
+
+  let input: syn::ItemFn = parse_macro_input!(item as syn::ItemFn);
+  let mut folder = RecursiveDescentFn {};
+  let output = folder.fold_item_fn(input);
+  TokenStream::from(quote!(#output))
+}

schala-lang/language/Cargo.toml

@@ -8,6 +8,9 @@ itertools = "0.5.8"
 take_mut = "0.1.3"
 maplit = "*"
 lazy_static = "0.2.8"
+failure = "0.1.2"
 
-schala-repl = { path = "../schala-repl" }
-schala-codegen = { path = "../schala-codegen" }
+
+schala-lang-codegen = { path = "../codegen" }
+schala-repl = { path = "../../schala-repl" }
+schala-repl-codegen = { path = "../../schala-repl-codegen" }

schala-lang/language/src/ast.rs

@@ -1,5 +1,7 @@
 use std::rc::Rc;
+use std::convert::From;
 
+use source_map::{SourceMap};
 use builtin::{BinOp, PrefixOp};
 
 #[derive(Debug, PartialEq)]
@@ -12,10 +14,9 @@ pub enum Statement {
 }
 
 pub type Block = Vec<Statement>;
-
 pub type ParamName = Rc<String>;
 pub type InterfaceName = Rc<String>; //should be a singleton I think??
-pub type FormalParam = (ParamName, Option<TypeName>);
+pub type FormalParam = (ParamName, Option<TypeIdentifier>);
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum Declaration {
@@ -33,7 +34,7 @@ pub enum Declaration {
     expr: Expression,
   },
   Impl {
-    type_name: TypeName,
+    type_name: TypeIdentifier,
     interface_name: Option<InterfaceName>,
     block: Vec<Declaration>,
   },
@@ -46,8 +47,9 @@ pub enum Declaration {
 #[derive(Debug, PartialEq, Clone)]
 pub struct Signature {
   pub name: Rc<String>,
+  pub operator: bool,
   pub params: Vec<FormalParam>,
-  pub type_anno: Option<TypeName>,
+  pub type_anno: Option<TypeIdentifier>,
 }
 
 #[derive(Debug, PartialEq, Clone)]
@@ -56,23 +58,29 @@ pub struct TypeBody(pub Vec<Variant>);
 #[derive(Debug, PartialEq, Clone)]
 pub enum Variant {
   UnitStruct(Rc<String>),
-  TupleStruct(Rc<String>, Vec<TypeName>),
-  Record(Rc<String>, Vec<(Rc<String>, TypeName)>),
+  TupleStruct(Rc<String>, Vec<TypeIdentifier>),
+  Record(Rc<String>, Vec<(Rc<String>, TypeIdentifier)>),
 }
 
 #[derive(Debug, PartialEq, Clone)]
-pub struct Expression(pub ExpressionType, pub Option<TypeName>);
+pub struct Expression(pub ExpressionType, pub Option<TypeIdentifier>);
+
+impl From<Expression> for SourceMap<Expression> {
+  fn from(node: Expression) -> Self {
+    SourceMap { node, data: None }
+  }
+}
 
 #[derive(Debug, PartialEq, Clone)]
-pub enum TypeName {
-  Tuple(Vec<TypeName>),
+pub enum TypeIdentifier {
+  Tuple(Vec<TypeIdentifier>),
   Singleton(TypeSingletonName)
 }
 
 #[derive(Debug, PartialEq, Clone)]
 pub struct TypeSingletonName {
   pub name: Rc<String>,
-  pub params: Vec<TypeName>,
+  pub params: Vec<TypeIdentifier>,
 }
 
 #[derive(Debug, PartialEq, Clone)]
@@ -111,10 +119,18 @@ pub enum ExpressionType {
   },
   Lambda {
     params: Vec<FormalParam>,
+    type_anno: Option<TypeIdentifier>,
     body: Block,
   },
   ListLiteral(Vec<Expression>),
 }
+
+impl From<ExpressionType> for SourceMap<ExpressionType> {
+  fn from(node: ExpressionType) -> Self {
+    SourceMap { node, data: None }
+  }
+}
+
 #[derive(Debug, PartialEq, Clone)]
 pub enum Discriminator {
   Simple(Expression),
@@ -157,7 +173,10 @@ pub enum Pattern {
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum PatternLiteral {
-  NumPattern(ExpressionType),
+  NumPattern {
+    neg: bool,
+    num: ExpressionType,
+  },
   StringPattern(Rc<String>),
   BoolPattern(bool),
   VarPattern(Rc<String>)

schala-lang/language/src/ast_visitor.rs

@@ -0,0 +1,157 @@
+use std::rc::Rc;
+
+use builtin::{PrefixOp, BinOp};
+use ast::*;
+
+pub fn dispatch<V: ASTVisitor>(visitor: &mut V, ast: &AST) {
+  for statement in ast.0.iter() {
+    match statement {
+      Statement::ExpressionStatement(e) => {
+        dispatch_expression(visitor, e);
+        visitor.expression(e);
+      },
+      Statement::Declaration(decl) => {
+        dispatch_declaration(visitor, decl);
+        visitor.declaration(decl);
+      },
+    };
+    visitor.statement(statement);
+  }
+  visitor.ast(ast)
+}
+
+fn dispatch_expression<V: ASTVisitor>(visitor: &mut V, expression: &Expression) {
+  match expression {
+    Expression(expr, maybe_anno) => {
+      match expr {
+        ExpressionType::NatLiteral(n) => visitor.nat_literal(n),
+        ExpressionType::FloatLiteral(f) => visitor.float_literal(f),
+        ExpressionType::StringLiteral(s) => visitor.string_literal(s),
+        ExpressionType::BoolLiteral(b) => visitor.bool_literal(b),
+        ExpressionType::BinExp(binop, lhs, rhs) => visitor.binop(binop, lhs, rhs),
+        ExpressionType::PrefixExp(prefix, expr) => visitor.prefixop(prefix, expr),
+        ExpressionType::TupleLiteral(v) => visitor.tuple_literal(v),
+        ExpressionType::Value(v) => visitor.value(v),
+        ExpressionType::NamedStruct { name, fields } => visitor.named_struct(name, fields),
+        ExpressionType::Call { f, arguments } => visitor.call(f, arguments),
+        ExpressionType::Index { indexee, indexers } => visitor.index(indexee, indexers),
+        ExpressionType::IfExpression { discriminator, body } => visitor.if_expression(discriminator, body),
+        ExpressionType::WhileExpression { condition, body } => visitor.while_expresssion(condition, body),
+        ExpressionType::ForExpression { enumerators, body } => visitor.for_expression(enumerators, body),
+        ExpressionType::Lambda { params, type_anno, body } => visitor.lambda_expression(params, type_anno, body),
+        ExpressionType::ListLiteral(items) => visitor.list_literal(items),
+      }
+      visitor.anno_expr(maybe_anno);
+      visitor.expr_kind(expr);
+    }
+  }
+}
+
+fn dispatch_declaration<V: ASTVisitor>(visitor: &mut V, declaration: &Declaration) {
+  match declaration {
+    Declaration::FuncSig(sig) => visitor.func_signature(sig),
+    Declaration::FuncDecl(sig, block) => visitor.func_declaration(sig, block),
+    Declaration::TypeDecl { name, body, mutable } => visitor.type_declaration(name, body, mutable),
+    Declaration::TypeAlias(alias, name) => visitor.type_alias(alias, name),
+    Declaration::Binding { name, constant, expr} => visitor.binding(name, constant, expr),
+    Declaration::Impl { type_name, interface_name, block } => visitor.impl_block(type_name, interface_name, block),
+    Declaration::Interface { name, signatures } => visitor.interface(name, signatures),
+  }
+}
+
+pub trait ASTVisitor {
+  fn ast(&mut self, _ast: &AST) { }
+  fn statement(&mut self, _stmt: &Statement) { }
+  fn expression(&mut self, _expr: &Expression) { }
+  fn anno_expr(&mut self, &Option<TypeIdentifier>) { }
+  fn expr_kind(&mut self, _expr: &ExpressionType) { }
+
+  fn nat_literal(&mut self, _n: &u64) { }
+  fn float_literal(&mut self, _f: &f64) { }
+  fn string_literal(&mut self, _s: &Rc<String>) { }
+  fn bool_literal(&mut self, _bool: &bool) { }
+  fn binop(&mut self, _binop: &BinOp, _lhs: &Expression, _rhs: &Expression) { }
+  fn prefixop(&mut self, prefix: &PrefixOp, _expr: &Expression) { }
+  fn tuple_literal(&mut self, _v: &Vec<Expression>) { }
+  fn value(&mut self, _v: &Rc<String>) { }
+  fn named_struct(&mut self, _name: &Rc<String>, _values: &Vec<(Rc<String>, Expression)>) { }
+  fn call(&mut self, _f: &Box<Expression>, _arguments: &Vec<Expression>) { }
+  fn index(&mut self, _indexee: &Box<Expression>, _indexers: &Vec<Expression>) { }
+  fn if_expression(&mut self, _discriminator: &Discriminator, _body: &IfExpressionBody) { }
+  fn while_expresssion(&mut self, _condition: &Option<Box<Expression>>, body: &Block) { }
+  fn for_expression(&mut self, _enumerators: &Vec<Enumerator>, _body: &Box<ForBody>) { }
+  fn lambda_expression(&mut self, _params: &Vec<FormalParam>, type_anno: &Option<TypeIdentifier>, body: &Block) { }
+  fn list_literal(&mut self, _items: &Vec<Expression>) { }
+
+
+  fn declaration(&mut self, _decl: &Declaration) { }
+  fn func_signature(&mut self, _sig: &Signature) { }
+  fn func_declaration(&mut self, _sig: &Signature, _block: &Vec<Statement>) { }
+  fn type_declaration(&mut self, _name: &TypeSingletonName, _body: &TypeBody, _mutable: &bool) { }
+  fn type_alias(&mut self, _alias: &Rc<String>, _name: &Rc<String>) { }
+  fn binding(&mut self, _name: &Rc<String>, _constant: &bool, _expr: &Expression) { }
+  fn impl_block(&mut self, _type_name: &TypeIdentifier, _interface_name: &Option<InterfaceName>, _block: &Vec<Declaration>) { }
+  fn interface(&mut self, name: &Rc<String>, signatures: &Vec<Signature>) { }
+}
+
+#[derive(Clone)]
+struct SchalaPrinter { 
+  s: String
+}
+
+impl SchalaPrinter {
+  fn new() -> SchalaPrinter {
+    SchalaPrinter {
+      s: format!("Schala source code:\n"),
+    }
+  }
+
+  fn done(self) -> String {
+    self.s
+  }
+}
+
+impl ASTVisitor for SchalaPrinter {
+  fn statement(&mut self, _: &Statement) {
+    self.s.push_str("\n");
+  }
+
+  fn expression(&mut self, _: &Expression) {
+    self.s.push_str("some_expr");
+  }
+
+  fn binding(&mut self, name: &Rc<String>, constant: &bool, _expr: &Expression) {
+    self.s.push_str(&format!("let{} {} = {}",
+                            if *constant { "" } else { " mut" }, 
+                            name,
+                            "some_expr"));
+  }
+}
+
+
+#[cfg(test)]
+mod visitor_tests {
+  use ::tokenizing::{Token, tokenize};
+  use ::parsing::ParseResult;
+  use ::ast::AST;
+  use super::*;
+
+  fn parse(input: &str) -> ParseResult<AST> {
+    let tokens = tokenize(input);
+    let mut parser = ::parsing::Parser::new(tokens);
+    parser.parse()
+  }
+
+  #[test]
+  fn test() {
+    let ast = parse("let a = 1 + 2; let b = 2 + 44;foo()").unwrap();
+    let mut pp = SchalaPrinter::new();
+    dispatch(&mut pp, &ast);
+    let result = pp.done();
+    assert_eq!(result, r#"Schala source code:
+let a = 1 + 2
+let b = 2 + 44
+foo()
+"#);
+  }
+}

schala-lang/language/src/builtin.rs

@@ -2,18 +2,19 @@ use std::rc::Rc;
 use std::collections::HashMap;
 use std::fmt;
 
-use self::Type::*; use self::TConstOld::*;
+use tokenizing::TokenKind;
+use self::BuiltinTypeSpecifier::*;
+use self::BuiltinTConst::*;
 
 
-//TODO get rid of these types and replace them with the right MonoType or whatever ones later
 #[derive(Debug, PartialEq, Clone)]
-pub enum Type {
-  Const(TConstOld),
-  Func(Box<Type>, Box<Type>),
+pub enum BuiltinTypeSpecifier {
+  Const(BuiltinTConst),
+  Func(Box<BuiltinTypeSpecifier>, Box<BuiltinTypeSpecifier>),
 }
 
 #[derive(Debug, PartialEq, Clone)]
-pub enum TConstOld {
+pub enum BuiltinTConst {
   Nat,
   Int,
   Float,
@@ -21,7 +22,7 @@ pub enum TConstOld {
   Bool,
 }
 
-impl fmt::Display for Type {
+impl fmt::Display for BuiltinTypeSpecifier {
   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
     write!(f, "{:?}", self)
   }
@@ -39,16 +40,53 @@ impl BinOp {
   pub fn sigil(&self) -> &Rc<String> {
     &self.sigil
   }
+  pub fn from_sigil_token(tok: &TokenKind) -> Option<BinOp> {
+    use self::TokenKind::*;
+    let s = match tok {
+      Operator(op) => op,
+      Period => ".",
+      Pipe => "|",
+      Slash => "/",
+      LAngleBracket => "<",
+      RAngleBracket => ">",
+      _ => 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()
   }
-  pub fn get_precedence(op: &str) -> i32 {
+  pub fn get_precedence_from_token(op: &TokenKind) -> Option<i32> {
+    use self::TokenKind::*;
+    let s = match op {
+      Operator(op) => op,
+      Period => ".",
+      Pipe => "|",
+      Slash => "/",
+      LAngleBracket => "<",
+      RAngleBracket => ">",
+      _ => return None
+    };
     let default = 10_000_000;
-    BINOPS.get(op).map(|x| x.2.clone()).unwrap_or(default)
+    Some(BINOPS.get(s).map(|x| x.2.clone()).unwrap_or_else(|| {
+      println!("Warning: operator {} not defined", s);
+      default
+    }))
+  }
+
+  pub fn get_precedence(&self) -> i32 {
+    let s: &str = &self.sigil;
+    let default = 10_000_000;
+    BINOPS.get(s).map(|x| x.2.clone()).unwrap_or_else(|| {
+      println!("Warning: operator {} not defined", s);
+      default
+    })
   }
 }
 
@@ -67,13 +105,15 @@ 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, (Type, ())> = 
+  static ref PREFIX_OPS: HashMap<&'static str, (BuiltinTypeSpecifier, ())> = 
     hashmap! {
       "+" => (Func(bx!(Const(Int)),  bx!(Const(Int))), ()),
       "-" => (Func(bx!(Const(Int)),  bx!(Const(Int))), ()),
@@ -84,7 +124,7 @@ lazy_static! {
 /* the second tuple member is a placeholder for when I want to make evaluation rules tied to the
  * binop definition */
 lazy_static! {
-  static ref BINOPS: HashMap<&'static str, (Type, (), i32)> =
+  static ref BINOPS: HashMap<&'static str, (BuiltinTypeSpecifier, (), 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),
@@ -96,5 +136,12 @@ lazy_static! {
       "^" => (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),
     };
 }

schala-lang/language/src/eval.rs

@@ -0,0 +1,747 @@
+
+use std::cell::RefCell;
+use std::rc::Rc;
+use std::fmt::Write;
+use std::io;
+
+use itertools::Itertools;
+
+use util::ScopeStack;
+use reduced_ast::{BoundVars, ReducedAST, Stmt, Expr, Lit, Func, Alternative, Subpattern};
+use symbol_table::{SymbolSpec, Symbol, SymbolTable};
+
+pub struct State<'a> {
+  values: ScopeStack<'a, Rc<String>, ValueEntry>,
+  symbol_table_handle: Rc<RefCell<SymbolTable>>,
+}
+
+macro_rules! builtin_binding {
+  ($name:expr, $values:expr) => {
+    $values.insert(Rc::new(format!($name)), ValueEntry::Binding { constant: true, val: Node::Expr(Expr::Func(Func::BuiltIn(Rc::new(format!($name))))) });
+  }
+}
+
+impl<'a> State<'a> {
+  pub fn new(symbol_table_handle: Rc<RefCell<SymbolTable>>) -> State<'a> {
+    let mut values = ScopeStack::new(Some(format!("global")));
+    builtin_binding!("print", values);
+    builtin_binding!("println", values);
+    builtin_binding!("getline", values);
+    State { values, symbol_table_handle }
+  }
+
+  pub fn debug_print(&self) -> String {
+    format!("Values: {:?}", self.values)
+  }
+
+  fn new_frame(&'a self, items: &'a Vec<Node>, bound_vars: &BoundVars) -> State<'a> {
+    let mut inner_state = State {
+      values: self.values.new_scope(None),
+      symbol_table_handle: self.symbol_table_handle.clone(),
+    };
+    for (bound_var, val) in bound_vars.iter().zip(items.iter()) {
+      if let Some(bv) = bound_var.as_ref() {
+        inner_state.values.insert(bv.clone(), ValueEntry::Binding { constant: true, val: val.clone() });
+      }
+    }
+    inner_state
+  }
+}
+
+#[derive(Debug, Clone)]
+enum Node {
+  Expr(Expr),
+  PrimObject {
+    name: Rc<String>,
+    tag: usize,
+    items: Vec<Node>,
+  },
+  PrimTuple {
+    items: Vec<Node>
+  }
+}
+
+fn paren_wrapped_vec(terms: impl Iterator<Item=String>) -> String {
+  let mut buf = String::new();
+  write!(buf, "(").unwrap();
+  for term in terms.map(|e| Some(e)).intersperse(None) {
+    match term {
+      Some(e) => write!(buf, "{}", e).unwrap(),
+      None => write!(buf, ", ").unwrap(),
+    };
+  }
+  write!(buf, ")").unwrap();
+  buf
+}
+
+
+impl Node {
+  fn to_repl(&self) -> String {
+    match self {
+      Node::Expr(e) => e.to_repl(),
+      Node::PrimObject { name, items, .. } if items.len() == 0 => format!("{}", name),
+      Node::PrimObject { name, items, .. } => format!("{}{}", name, paren_wrapped_vec(items.iter().map(|x| x.to_repl()))),
+      Node::PrimTuple { items } => format!("{}", paren_wrapped_vec(items.iter().map(|x| x.to_repl()))),
+    }
+  }
+  fn is_true(&self) -> bool {
+    match self {
+      Node::Expr(Expr::Lit(::reduced_ast::Lit::Bool(true))) => true,
+      _ => false,
+    }
+  }
+}
+
+#[derive(Debug)]
+enum ValueEntry {
+  Binding {
+    constant: bool,
+    val: /*FullyEvaluatedExpr*/ Node, //TODO make this use a subtype to represent fully evaluatedness
+  }
+}
+
+type EvalResult<T> = Result<T, String>;
+
+impl Expr {
+  fn to_node(self) -> Node {
+    Node::Expr(self)
+  }
+  fn to_repl(&self) -> String {
+    use self::Lit::*;
+    use self::Func::*;
+
+    match self {
+      Expr::Lit(ref l) => match l {
+        Nat(n) => format!("{}", n),
+        Int(i) => format!("{}", i),
+        Float(f) => format!("{}", f),
+        Bool(b) => format!("{}", b),
+        StringLit(s) => format!("\"{}\"", s),
+      },
+      Expr::Func(f) => match f {
+        BuiltIn(name) => format!("<built-in function '{}'>", name),
+        UserDefined { name: None, .. } => format!("<function>"),
+        UserDefined { name: Some(name), .. } => format!("<function '{}'>", name),
+      },
+      Expr::Constructor { 
+        type_name: _, name, arity, ..
+      } => if *arity == 0 {
+        format!("{}", name)
+      } else {
+        format!("<data constructor '{}'>", name)
+      },
+      Expr::Tuple(exprs) => paren_wrapped_vec(exprs.iter().map(|x| x.to_repl())),
+      _ => format!("{:?}", self),
+    }
+  }
+
+  fn replace_conditional_target_sigil(self, replacement: &Expr) -> Expr {
+    use self::Expr::*;
+
+    match self {
+      ConditionalTargetSigilValue => replacement.clone(),
+      Unit | Lit(_) | Func(_) | Val(_) | Constructor { .. } |
+       CaseMatch { .. } | UnimplementedSigilValue => self,
+      Tuple(exprs) => Tuple(exprs.into_iter().map(|e| e.replace_conditional_target_sigil(replacement)).collect()),
+      Call { f, args } => {
+        let new_args = args.into_iter().map(|e| e.replace_conditional_target_sigil(replacement)).collect();
+        Call { f, args: new_args }
+      },
+      Conditional { .. } => panic!("Dunno if I need this, but if so implement"),
+      Assign { .. } => panic!("I'm pretty sure I don't need this"),
+    }
+  }
+}
+
+impl<'a> State<'a> {
+  pub fn evaluate(&mut self, ast: ReducedAST, repl: bool) -> Vec<Result<String, String>> {
+    let mut acc = vec![];
+
+    // handle prebindings
+    for statement in ast.0.iter() {
+      self.prebinding(statement);
+    }
+
+    for statement in ast.0 {
+      match self.statement(statement) {
+        Ok(Some(ref output)) if repl => acc.push(Ok(output.to_repl())),
+        Ok(_) => (),
+        Err(error) => {
+          acc.push(Err(format!("Runtime error: {}", error)));
+          return acc;
+        },
+      }
+    }
+    acc
+  }
+
+  fn prebinding(&mut self, stmt: &Stmt) {
+    match stmt {
+      Stmt::PreBinding { name, func } => {
+        let v_entry = ValueEntry::Binding { constant: true, val: Node::Expr(Expr::Func(func.clone())) };
+        self.values.insert(name.clone(), v_entry);
+      },
+      Stmt::Expr(_expr) => {
+        //TODO have this support things like nested function defs
+
+      },
+      _ => ()
+    }
+  }
+
+  fn statement(&mut self, stmt: Stmt) -> EvalResult<Option<Node>> {
+    match stmt {
+      Stmt::Binding { name, constant, expr } => {
+        let val = self.expression(Node::Expr(expr))?;
+        self.values.insert(name.clone(), ValueEntry::Binding { constant, val });
+        Ok(None)
+      },
+      Stmt::Expr(expr) => Ok(Some(self.expression(expr.to_node())?)),
+      Stmt::PreBinding {..} | Stmt::Noop => Ok(None),
+    }
+  }
+
+  fn block(&mut self, stmts: Vec<Stmt>) -> EvalResult<Node> {
+    let mut ret = None;
+    for stmt in stmts {
+      ret = self.statement(stmt)?;
+    }
+    Ok(ret.unwrap_or(Node::Expr(Expr::Unit)))
+  }
+
+  fn expression(&mut self, node: Node) -> EvalResult<Node> {
+    use self::Expr::*;
+    match node {
+      t @ Node::PrimTuple { .. } => Ok(t),
+      obj @ Node::PrimObject { .. } =>  Ok(obj),
+      Node::Expr(expr) => match expr {
+        literal @ Lit(_) => Ok(Node::Expr(literal)),
+        Call { box f, args } => self.call_expression(f, args),
+        Val(v) => self.value(v),
+        Constructor { arity, ref name, tag, .. } if arity == 0 => Ok(Node::PrimObject { name: name.clone(), tag, items: vec![] }),
+        constructor @ Constructor { .. } => Ok(Node::Expr(constructor)),
+        func @ Func(_) => Ok(Node::Expr(func)),
+        Tuple(exprs) => {
+          let nodes = exprs.into_iter().map(|expr| self.expression(Node::Expr(expr))).collect::<Result<Vec<Node>,_>>()?;
+          Ok(Node::PrimTuple { items: nodes })
+        },
+        Conditional { box cond, then_clause, else_clause } => self.conditional(cond, then_clause, else_clause),
+        Assign { box val, box expr } => self.assign_expression(val, expr),
+        Unit => Ok(Node::Expr(Unit)),
+        CaseMatch { box cond, alternatives } => self.case_match_expression(cond, alternatives),
+        ConditionalTargetSigilValue => Ok(Node::Expr(ConditionalTargetSigilValue)),
+        UnimplementedSigilValue => Err(format!("Sigil value eval not implemented")),
+      }
+    }
+  }
+
+  fn call_expression(&mut self, f: Expr, args: Vec<Expr>) -> EvalResult<Node> {
+    use self::Expr::*;
+    match self.expression(Node::Expr(f))? {
+      Node::Expr(Constructor { type_name, name, tag, arity }) => self.apply_data_constructor(type_name, name, tag, arity, args),
+      Node::Expr(Func(f)) => self.apply_function(f, args),
+      other => return Err(format!("Tried to call {:?} which is not a function or data constructor", other)),
+    }
+  }
+
+  fn apply_data_constructor(&mut self, _type_name: Rc<String>, name: Rc<String>, tag: usize, arity: usize, args: Vec<Expr>) -> EvalResult<Node> {
+    if arity != args.len() {
+      return Err(format!("Data constructor {} requires {} args", name, arity));
+    }
+
+    let evaled_args = args.into_iter().map(|expr| self.expression(Node::Expr(expr))).collect::<Result<Vec<Node>,_>>()?;
+    //let evaled_args = vec![];
+    Ok(Node::PrimObject {
+      name: name.clone(),
+      items: evaled_args,
+      tag 
+    })
+  }
+
+  fn apply_function(&mut self, f: Func, args: Vec<Expr>) -> EvalResult<Node> {
+    match f {
+      Func::BuiltIn(sigil) => Ok(Node::Expr(self.apply_builtin(sigil, args)?)),
+      Func::UserDefined { params, body, name } => {
+
+        if params.len() != args.len() {
+          return Err(format!("calling a {}-argument function with {} args", params.len(), args.len()))
+        }
+        let mut func_state = State {
+          values: self.values.new_scope(name.map(|n| format!("{}", n))),
+          symbol_table_handle: self.symbol_table_handle.clone(),
+        };
+        for (param, val) in params.into_iter().zip(args.into_iter()) {
+          let val = func_state.expression(Node::Expr(val))?;
+          func_state.values.insert(param, ValueEntry::Binding { constant: true, val });
+        }
+        // TODO figure out function return semantics
+        func_state.block(body)
+      }
+    }
+  }
+
+  fn apply_builtin(&mut self, name: Rc<String>, args: Vec<Expr>) -> EvalResult<Expr> {
+    use self::Expr::*;
+    use self::Lit::*;
+    let evaled_args: Result<Vec<Expr>, String> = args.into_iter().map(|arg| {
+      match self.expression(Node::Expr(arg)) {
+        Ok(Node::Expr(e)) => Ok(e),
+        Ok(Node::PrimTuple { .. }) => Err(format!("Trying to apply a builtin to a tuple")),
+        Ok(Node::PrimObject { .. }) => Err(format!("Trying to apply a builtin to a primitive object")),
+        Err(e) => Err(e)
+      }
+    }).collect();
+    let evaled_args = evaled_args?;
+
+    Ok(match (name.as_str(), evaled_args.as_slice()) {
+      /* binops */
+      ("+", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l + r)),
+      ("++", &[Lit(StringLit(ref s1)), Lit(StringLit(ref s2))]) => Lit(StringLit(Rc::new(format!("{}{}", s1, s2)))),
+      ("-", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l - r)),
+      ("*", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l * r)),
+      ("/", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Float((l as f64)/ (r as f64))),
+      ("//", &[Lit(Nat(l)), Lit(Nat(r))]) => if r == 0 {
+        return Err(format!("divide by zero"));
+      } else {
+        Lit(Nat(l / r))
+      },
+      ("%", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l % r)),
+      ("^", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l ^ r)),
+      ("&", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l & r)),
+      ("|", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l | r)),
+
+      /* comparisons */
+      ("==", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l == r)),
+      ("==", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l == r)),
+      ("==", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l == r)),
+      ("==", &[Lit(Bool(l)), Lit(Bool(r))]) => Lit(Bool(l == r)),
+      ("==", &[Lit(StringLit(ref l)), Lit(StringLit(ref r))]) => Lit(Bool(l == r)),
+
+      ("<", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l < r)),
+      ("<", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l < r)),
+      ("<", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l < r)),
+
+      ("<=", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l <= r)),
+      ("<=", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l <= r)),
+      ("<=", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l <= r)),
+
+      (">", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l > r)),
+      (">", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l > r)),
+      (">", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l > r)),
+
+      (">=", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l >= r)),
+      (">=", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l >= r)),
+      (">=", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l >= r)),
+
+      /* prefix ops */
+      ("!", &[Lit(Bool(true))]) => Lit(Bool(false)),
+      ("!", &[Lit(Bool(false))]) => Lit(Bool(true)),
+      ("-", &[Lit(Nat(n))]) => Lit(Int(-1*(n as i64))),
+      ("-", &[Lit(Int(n))]) => Lit(Int(-1*(n as i64))),
+      ("+", &[Lit(Int(n))]) => Lit(Int(n)),
+      ("+", &[Lit(Nat(n))]) => Lit(Nat(n)),
+
+
+      /* builtin functions */
+      ("print", &[ref anything]) => {
+        print!("{}", anything.to_repl());
+        Expr::Unit
+      },
+      ("println", &[ref anything]) => {
+        println!("{}", anything.to_repl());
+        Expr::Unit
+      },
+      ("getline", &[]) => {
+        let mut buf = String::new();
+        io::stdin().read_line(&mut buf).expect("Error readling line in 'getline'");
+        Lit(StringLit(Rc::new(buf.trim().to_string())))
+      },
+      (x, args) => return Err(format!("bad or unimplemented builtin {:?} | {:?}", x, args)),
+    })
+  }
+
+  fn conditional(&mut self, cond: Expr, then_clause: Vec<Stmt>, else_clause: Vec<Stmt>) -> EvalResult<Node> {
+    let cond = self.expression(Node::Expr(cond))?;
+    Ok(match cond {
+      Node::Expr(Expr::Lit(Lit::Bool(true))) =>  self.block(then_clause)?,
+      Node::Expr(Expr::Lit(Lit::Bool(false))) => self.block(else_clause)?,
+      _ => return Err(format!("Conditional with non-boolean condition"))
+    })
+  }
+
+  fn assign_expression(&mut self, val: Expr, expr: Expr) -> EvalResult<Node> {
+    let name = match val  {
+      Expr::Val(name) => name,
+      _ => return Err(format!("Trying to assign to a non-value")),
+    };
+
+    let constant = match self.values.lookup(&name) {
+      None => return Err(format!("Constant {} is undefined", name)),
+      Some(ValueEntry::Binding { constant, .. }) => constant.clone(),
+    };
+    if constant {
+      return Err(format!("trying to update {}, a non-mutable binding", name));
+    }
+    let val = self.expression(Node::Expr(expr))?;
+    self.values.insert(name.clone(), ValueEntry::Binding { constant: false, val });
+    Ok(Node::Expr(Expr::Unit))
+  }
+
+  fn guard_passes(&mut self, guard: &Option<Expr>, cond: &Node) -> EvalResult<bool> {
+    if let Some(ref guard_expr) = guard {
+      let guard_expr = match cond {
+        Node::Expr(ref e) => guard_expr.clone().replace_conditional_target_sigil(e),
+        _ => guard_expr.clone()
+      };
+      Ok(self.expression(guard_expr.to_node())?.is_true())
+    } else {
+      Ok(true)
+    }
+  }
+
+  fn case_match_expression(&mut self, cond: Expr, alternatives: Vec<Alternative>) -> EvalResult<Node> {
+
+    //TODO need to handle recursive subpatterns
+    let all_subpatterns_pass = |state: &mut State, subpatterns: &Vec<Option<Subpattern>>, items: &Vec<Node>| -> EvalResult<bool> {
+
+      if subpatterns.len() == 0 {
+        return Ok(true)
+      }
+
+      if items.len() != subpatterns.len() {
+        return Err(format!("Subpattern length isn't correct items {} subpatterns {}", items.len(), subpatterns.len()));
+      }
+
+      for (maybe_subp, cond) in subpatterns.iter().zip(items.iter()) {
+        if let Some(subp) = maybe_subp {
+          if !state.guard_passes(&subp.guard, &cond)? {
+            return Ok(false)
+          }
+        }
+      }
+      Ok(true)
+    };
+
+    let cond = self.expression(Node::Expr(cond))?;
+    for alt in alternatives {
+      // no matter what type of condition we have, ignore alternative if the guard evaluates false
+      if !self.guard_passes(&alt.guard, &cond)? {
+        continue;
+      }
+
+      match cond {
+        Node::PrimObject { ref tag, ref items, .. } => {
+          if alt.tag.map(|t| t == *tag).unwrap_or(true) {
+            let mut inner_state = self.new_frame(items, &alt.bound_vars);
+            if all_subpatterns_pass(&mut inner_state, &alt.subpatterns, items)? {
+              return inner_state.block(alt.item);
+            } else {
+              continue;
+            }
+          }
+        },
+        Node::PrimTuple { ref items } =>  {
+          let mut inner_state = self.new_frame(items, &alt.bound_vars);
+          if all_subpatterns_pass(&mut inner_state, &alt.subpatterns, items)? {
+            return inner_state.block(alt.item);
+          } else {
+            continue;
+          }
+        },
+        Node::Expr(ref _e) => {
+          if let None = alt.tag {
+            return self.block(alt.item)
+          }
+        }
+      }
+    }
+    Err(format!("{:?} failed pattern match", cond))
+  }
+
+  fn value(&mut self, name: Rc<String>) -> EvalResult<Node> {
+    use self::ValueEntry::*;
+    use self::Func::*;
+    //TODO add a layer of indirection here to talk to the symbol table first, and only then look up
+    //in the values table
+
+    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 {
+        //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 {
+            Node::PrimObject { name: name.clone(), tag: 0, items: vec![] }
+          } else {
+            return Err(format!("This data constructor thing not done"))
+          }
+        },
+        SymbolSpec::Func(_) => match self.values.lookup(&name) {
+          Some(Binding { val: Node::Expr(Expr::Func(UserDefined { name, params, body })), .. }) => {
+            Node::Expr(Expr::Func(UserDefined { name: name.clone(), params: params.clone(), body: body.clone() }))
+          },
+          _ => unreachable!(),
+        },
+      },
+      /* see if it's an ordinary variable TODO make variables go in symbol table */
+      None => match self.values.lookup(&name) {
+        Some(Binding { val, .. }) => val.clone(),
+        None => return Err(format!("Couldn't find value {}", name)),
+      }
+    })
+  }
+}
+
+#[cfg(test)]
+mod eval_tests {
+  use std::cell::RefCell;
+  use std::rc::Rc;
+
+  use tokenizing::{Token, tokenize};
+  use ::parsing::ParseResult;
+  use ::ast::AST;
+  use symbol_table::SymbolTable;
+  use eval::State;
+
+  fn parse(tokens: Vec<Token>) -> ParseResult<AST> {
+    let mut parser = ::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();
+    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);
+    all_output
+  }
+
+  macro_rules! test_in_fresh_env {
+    ($string:expr, $correct:expr) => {
+      {
+        let all_output = evaluate_all_outputs($string);
+        let ref output = all_output.last().unwrap();
+        assert_eq!(**output, Ok($correct.to_string()));
+      }
+    }
+  }
+
+  #[test]
+  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]
+  fn function_eval() {
+    test_in_fresh_env!("fn oi(x) { x + 1 }; oi(4)", "5");
+    test_in_fresh_env!("fn oi(x) { x + 1 }; oi(1+2)", "4");
+  }
+
+  #[test]
+  fn scopes() {
+    let scope_ok = r#"
+    let a = 20
+    fn haha() {
+      let a = 10
+      a
+    }
+    haha()
+    "#;
+    test_in_fresh_env!(scope_ok, "10");
+    let scope_ok = r#"
+    let a = 20
+    fn haha() {
+      let a = 10
+      a
+    }
+    a
+    "#;
+    test_in_fresh_env!(scope_ok, "20");
+  }
+
+  #[test]
+  fn if_is_patterns() {
+    let source = r#"
+type Option<T> = Some(T) | None
+let x = Some(9); if x is Some(q) then { q } else { 0 }"#;
+    test_in_fresh_env!(source, "9");
+
+    let source = r#"
+type Option<T> = Some(T) | None
+let x = None; if x is Some(q) then { q } else { 0 }"#;
+    test_in_fresh_env!(source, "0");
+  }
+
+  #[test]
+  fn full_if_matching() {
+    let source = r#"
+type Option<T> = Some(T) | None
+let a = None
+if a { is None -> 4, is Some(x) -> x }
+"#;
+  test_in_fresh_env!(source, "4");
+
+    let source = r#"
+type Option<T> = Some(T) | None
+let a = Some(99)
+if a { is None -> 4, is Some(x) -> x }
+"#;
+  test_in_fresh_env!(source, "99");
+
+  let source = r#"
+let a = 10
+if a { is 10 -> "x", is 4 -> "y" }
+"#;
+  test_in_fresh_env!(source, "\"x\"");
+
+  let source = r#"
+let a = 10
+if a { is 15 -> "x", is 10 -> "y" }
+"#;
+  test_in_fresh_env!(source, "\"y\"");
+  }
+
+  #[test]
+  fn string_pattern() {
+    let source = r#"
+let a = "foo"
+if a { is "foo" -> "x", is _ -> "y" }
+"#;
+    test_in_fresh_env!(source, "\"x\"");
+  }
+
+  #[test]
+  fn boolean_pattern() {
+    let source = r#"
+let a = true
+if a { 
+  is true -> "x",
+  is false -> "y"
+}
+"#;
+    test_in_fresh_env!(source, "\"x\"");
+  }
+
+  #[test]
+  fn boolean_pattern_2() {
+    let source = r#"
+let a = false
+if a { is true -> "x", is false -> "y" }
+"#;
+    test_in_fresh_env!(source, "\"y\"");
+  }
+
+  #[test]
+  fn ignore_pattern() {
+    let source = r#"
+type Option<T> = Some(T) | None
+if Some(10) {
+  is _ -> "hella"
+}
+"#;
+    test_in_fresh_env!(source, "\"hella\"");
+  }
+
+  #[test]
+  fn tuple_pattern() {
+    let source = r#"
+if (1, 2) {
+  is (1, x) -> x,
+  is _ -> 99
+}
+"#;
+    test_in_fresh_env!(source, 2);
+  }
+
+
+  #[test]
+  fn tuple_pattern_2() {
+    let source = r#"
+if (1, 2) {
+  is (10, x) -> x,
+  is (y, x) -> x + y
+}
+"#;
+    test_in_fresh_env!(source, 3);
+  }
+
+  #[test]
+  fn tuple_pattern_3() {
+    let source = r#"
+if (1, 5) {
+  is (10, x) -> x,
+  is (1, x) -> x
+}
+"#;
+    test_in_fresh_env!(source, 5);
+  }
+
+  #[test]
+  fn tuple_pattern_4() {
+    let source = r#"
+if (1, 5) {
+  is (10, x) -> x,
+  is (1, x) -> x,
+}
+"#;
+    test_in_fresh_env!(source, 5);
+  }
+
+  #[test]
+  fn  prim_obj_pattern() {
+    let source = r#"
+type Stuff = Mulch(Nat) | Jugs(Nat, String) | Mardok
+let a = Mulch(20)
+let b = Jugs(1, "haha")
+let c = Mardok
+
+let x = if a {
+  is Mulch(20) -> "x",
+  is _ -> "ERR"
+}
+
+let y = if b {
+  is Mulch(n) -> "ERR",
+  is Jugs(2, _) -> "ERR",
+  is Jugs(1, s) -> s,
+  is _ -> "ERR",
+}
+
+let z = if c {
+  is Jugs(_, _) -> "ERR",
+  is Mardok -> "NIGH",
+  is _ -> "ERR",
+}
+
+(x, y, z)
+"#;
+  test_in_fresh_env!(source, r#"("x", "haha", "NIGH")"#);
+  }
+
+  #[test]
+  fn basic_lambda_syntax() {
+    let source = r#"
+let q = \(x, y) { x * y }
+let x = q(5,2)
+let y = \(m, n, o) { m + n + o }(1,2,3)
+(x, y)
+  "#;
+  test_in_fresh_env!(source, r"(10, 6)");
+  }
+
+  #[test]
+  fn lambda_syntax_2() {
+    let source = r#"
+fn milta() {
+  \(x) { x + 33 }
+}
+milta()(10)
+  "#;
+    test_in_fresh_env!(source, "43");
+  }
+}

schala-lang/language/src/lib.rs

@@ -1,15 +1,22 @@
 #![feature(trace_macros)]
+#![feature(custom_attribute)]
+#![feature(unrestricted_attribute_tokens)]
 #![feature(slice_patterns, box_patterns, box_syntax)]
-#![feature(proc_macro)]
+
+//! `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
+//! `ProgrammingLanguageInterface` and the chain of compiler passes for it.
+
 extern crate itertools;
 #[macro_use]
 extern crate lazy_static;
 #[macro_use]
 extern crate maplit;
-#[macro_use]
 extern crate schala_repl;
 #[macro_use]
-extern crate schala_codegen;
+extern crate schala_repl_codegen;
+#[macro_use]
+extern crate schala_lang_codegen;
 
 use std::cell::RefCell;
 use std::rc::Rc;
@@ -22,9 +29,11 @@ macro_rules! bx {
 }
 
 mod util;
+mod source_map;
 mod builtin;
 mod tokenizing;
 mod ast;
+mod ast_visitor;
 mod parsing;
 mod symbol_table;
 mod typechecking;
@@ -36,27 +45,44 @@ mod eval;
 #[LanguageName = "Schala"]
 #[SourceFileExtension = "schala"]
 #[PipelineSteps(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 {
   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 {
       symbol_table: symbols.clone(),
-      type_context: typechecking::TypeContext::new(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 = r#"
-type Option<T> = Some(T) | None
-    "#;
+    let prelude = include_str!("prelude.schala");
     let mut s = Schala::new_blank_env();
     s.execute_pipeline(prelude, &EvalOptions::default());
     s
@@ -66,7 +92,7 @@ type Option<T> = Some(T) | None
 fn tokenizing(_handle: &mut Schala, input: &str, comp: Option<&mut UnfinishedComputation>) -> Result<Vec<tokenizing::Token>, String> {
   let tokens = tokenizing::tokenize(input);
   comp.map(|comp| {
-    let token_string = tokens.iter().map(|t| format!("{:?}<L:{},C:{}>", t.token_type, t.offset.0, t.offset.1)).join(", ");
+    let token_string = tokens.iter().map(|t| format!("{:?}<L:{},C:{}>", t.kind, t.offset.0, t.offset.1)).join(", ");
     comp.add_artifact(TraceArtifact::new("tokens", token_string));
   });
 
@@ -78,9 +104,17 @@ fn tokenizing(_handle: &mut Schala, input: &str, comp: Option<&mut UnfinishedCom
   }
 }
 
-fn parsing(_handle: &mut Schala, input: Vec<tokenizing::Token>, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
+fn parsing(handle: &mut Schala, input: Vec<tokenizing::Token>, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
+  use 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();
 
-  let (ast, trace) = parsing::parse(input);
   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());
@@ -108,22 +142,14 @@ fn symbol_table(handle: &mut Schala, input: ast::AST, comp: Option<&mut Unfinish
 }
 
 fn typechecking(handle: &mut Schala, input: ast::AST, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
-  match handle.type_context.type_check_ast(&input) {
-    Ok(ty) => {
-      comp.map(|c| {
-        c.add_artifact(TraceArtifact::new("type_table", format!("{}", handle.type_context.debug_types())));
-        c.add_artifact(TraceArtifact::new("type_check", format!("{:?}", ty)));
-      });
-      Ok(input)
-    },
-    Err(msg) => {
-      comp.map(|comp| {
-        comp.add_artifact(TraceArtifact::new("type_table", format!("{}", handle.type_context.debug_types())));
-        comp.add_artifact(TraceArtifact::new("type_check", format!("Type error: {:?}", msg)));
-      });
-      Ok(input)
-    }
-  }
+  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(handle: &mut Schala, input: ast::AST, comp: Option<&mut UnfinishedComputation>) -> Result<reduced_ast::ReducedAST, String> {

schala-lang/language/src/prelude.schala

@@ -0,0 +1,13 @@
+
+type Option<T> = Some(T) | None
+type Color = Red | Green | Blue
+type Ord = LT | EQ | GT
+
+
+fn map(input: Option<T>, func: Func): Option<T> {
+  if input {
+    is Some(x) -> Some(func(x)),
+    is None -> None,
+  }
+}
+  

schala-lang/language/src/reduced_ast.rs

@@ -0,0 +1,394 @@
+use std::rc::Rc;
+
+use ast::*;
+use symbol_table::{Symbol, SymbolSpec, SymbolTable};
+use builtin::{BinOp, PrefixOp};
+
+#[derive(Debug)]
+pub struct ReducedAST(pub Vec<Stmt>);
+
+#[derive(Debug, Clone)]
+pub enum Stmt {
+  PreBinding {
+    name: Rc<String>,
+    func: Func,
+  },
+  Binding {
+    name: Rc<String>,
+    constant: bool,
+    expr: Expr,
+  },
+  Expr(Expr),
+  Noop,
+}
+
+#[derive(Debug, Clone)]
+pub enum Expr {
+  Unit,
+  Lit(Lit),
+  Tuple(Vec<Expr>),
+  Func(Func),
+  Val(Rc<String>),
+  Constructor {
+    type_name: Rc<String>,
+    name: Rc<String>,
+    tag: usize,
+    arity: usize,
+  },
+  Call {
+    f: Box<Expr>,
+    args: Vec<Expr>,
+  },
+  Assign {
+    val: Box<Expr>,
+    expr: Box<Expr>,
+  },
+  Conditional {
+    cond: Box<Expr>,
+    then_clause: Vec<Stmt>,
+    else_clause: Vec<Stmt>,
+  },
+  ConditionalTargetSigilValue,
+  CaseMatch {
+    cond: Box<Expr>,
+    alternatives: Vec<Alternative>
+  },
+  UnimplementedSigilValue
+}
+
+pub type BoundVars = Vec<Option<Rc<String>>>; //remember that order matters here
+
+#[derive(Debug, Clone)]
+pub struct Alternative {
+  pub tag: Option<usize>,
+  pub subpatterns: Vec<Option<Subpattern>>,
+  pub guard: Option<Expr>,
+  pub bound_vars: BoundVars,
+  pub item: Vec<Stmt>,
+}
+
+#[derive(Debug, Clone)]
+pub struct Subpattern {
+  pub tag: Option<usize>,
+  pub subpatterns: Vec<Option<Subpattern>>,
+  pub bound_vars: BoundVars,
+  pub guard: Option<Expr>,
+}
+
+#[derive(Debug, Clone)]
+pub enum Lit {
+  Nat(u64),
+  Int(i64),
+  Float(f64),
+  Bool(bool),
+  StringLit(Rc<String>),
+}
+
+#[derive(Debug, Clone)]
+pub enum Func {
+  BuiltIn(Rc<String>),
+  UserDefined {
+    name: Option<Rc<String>>,
+    params: Vec<Rc<String>>,
+    body: Vec<Stmt>,
+  }
+}
+
+impl AST {
+  pub fn reduce(&self, symbol_table: &SymbolTable) -> ReducedAST {
+    let mut output = vec![];
+    for statement in self.0.iter() {
+      output.push(statement.reduce(symbol_table));
+    }
+    ReducedAST(output)
+  }
+}
+
+impl Statement {
+  fn reduce(&self, symbol_table: &SymbolTable) -> Stmt { 
+    use ast::Statement::*;
+    match self {
+      ExpressionStatement(expr) => Stmt::Expr(expr.reduce(symbol_table)),
+      Declaration(decl) => decl.reduce(symbol_table),
+    }
+  }
+}
+
+impl Expression {
+  fn reduce(&self, symbol_table: &SymbolTable) -> Expr {
+    use ast::ExpressionType::*;
+    let ref input = self.0;
+    match input {
+      NatLiteral(n) => Expr::Lit(Lit::Nat(*n)),
+      FloatLiteral(f) => Expr::Lit(Lit::Float(*f)),
+      StringLiteral(s) => Expr::Lit(Lit::StringLit(s.clone())),
+      BoolLiteral(b) => Expr::Lit(Lit::Bool(*b)),
+      BinExp(binop, lhs, rhs) => binop.reduce(symbol_table, lhs, rhs),
+      PrefixExp(op, arg) => op.reduce(symbol_table, arg),
+      Value(name) => match symbol_table.lookup_by_name(name) {
+        Some(Symbol { spec: SymbolSpec::DataConstructor { index, type_args, type_name}, .. }) => Expr::Constructor {
+          type_name: type_name.clone(),
+          name: name.clone(),
+          tag: index.clone(),
+          arity: type_args.len(),
+        },
+        _ => Expr::Val(name.clone()),
+      },
+      Call { f, arguments } => Expr::Call {
+        f: Box::new(f.reduce(symbol_table)),
+        args: arguments.iter().map(|arg| arg.reduce(symbol_table)).collect(),
+      },
+      TupleLiteral(exprs) => Expr::Tuple(exprs.iter().map(|e| e.reduce(symbol_table)).collect()),
+      IfExpression { discriminator, body } => reduce_if_expression(discriminator, body, symbol_table),
+      Lambda { params, body, .. } => reduce_lambda(params, body, symbol_table),
+      NamedStruct { .. } => Expr::UnimplementedSigilValue,
+      Index { .. } => Expr::UnimplementedSigilValue,
+      WhileExpression { .. } => Expr::UnimplementedSigilValue,
+      ForExpression { .. } => Expr::UnimplementedSigilValue,
+      ListLiteral { .. } => Expr::UnimplementedSigilValue,
+    }
+  }
+}
+
+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(),
+    body: body.iter().map(|stmt| stmt.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),
+    Discriminator::BinOp(ref _expr, ref _binop) => panic!("Can't yet handle binop discriminators")
+  });
+  match *body {
+    IfExpressionBody::SimpleConditional(ref then_clause, ref else_clause) => {
+      let then_clause = then_clause.iter().map(|expr| expr.reduce(symbol_table)).collect();
+      let else_clause = match else_clause {
+        None => vec![],
+        Some(stmts) => stmts.iter().map(|expr| expr.reduce(symbol_table)).collect(),
+      };
+      Expr::Conditional { cond, then_clause, else_clause }
+    },
+    IfExpressionBody::SimplePatternMatch(ref pat, ref then_clause, ref else_clause) => {
+      let then_clause = then_clause.iter().map(|expr| expr.reduce(symbol_table)).collect();
+      let else_clause = match else_clause {
+        None => vec![],
+        Some(stmts) => stmts.iter().map(|expr| expr.reduce(symbol_table)).collect(),
+      };
+
+      let alternatives = vec![
+        pat.to_alternative(then_clause, symbol_table),
+        Alternative {
+          tag: None,
+          subpatterns: vec![],
+          bound_vars: vec![],
+          guard: None,
+          item: else_clause
+        },
+      ];
+
+      Expr::CaseMatch {
+        cond,
+        alternatives,
+      }
+    },
+    IfExpressionBody::GuardList(ref guard_arms) => {
+      let mut alternatives = vec![];
+      for arm in guard_arms {
+        match arm.guard {
+          Guard::Pat(ref p) =>  {
+            let item = arm.body.iter().map(|expr| expr.reduce(symbol_table)).collect();
+            let alt = p.to_alternative(item, symbol_table);
+            alternatives.push(alt);
+          },
+          Guard::HalfExpr(HalfExpr { op: _, expr: _ }) => {
+            return Expr::UnimplementedSigilValue
+          }
+        }
+      }
+      Expr::CaseMatch { cond, alternatives }
+    }
+  }
+}
+/*                     ig var   pat
+ * x is SomeBigOldEnum(_, x, Some(t))
+ */
+
+fn handle_symbol(symbol: Option<&Symbol>, inner_patterns: &Vec<Pattern>, symbol_table: &SymbolTable) -> Subpattern {
+  use self::Pattern::*;
+  let tag = symbol.map(|symbol| match symbol.spec {
+    SymbolSpec::DataConstructor { index, .. } => index.clone(),
+    _ => panic!("Symbol is not a data constructor - this should've been caught in type-checking"),
+  });
+  let bound_vars = inner_patterns.iter().map(|p| match p {
+    Literal(PatternLiteral::VarPattern(var)) => Some(var.clone()),
+    _ => None,
+  }).collect();
+
+  let subpatterns = inner_patterns.iter().map(|p| match p {
+    Ignored => None,
+    Literal(PatternLiteral::VarPattern(_)) => None,
+    Literal(other) => Some(other.to_subpattern(symbol_table)),
+    tp @ TuplePattern(_) => Some(tp.to_subpattern(symbol_table)),
+    ts @ TupleStruct(_, _) => Some(ts.to_subpattern(symbol_table)),
+    Record(..) => unimplemented!(),
+  }).collect();
+
+  let guard = None;
+  /*
+     let guard_equality_exprs: Vec<Expr> = subpatterns.iter().map(|p| match p {
+     Literal(lit) => match lit {
+     _ => unimplemented!()
+     },
+     _ => unimplemented!()
+     }).collect();
+     */
+
+  Subpattern {
+    tag,
+    subpatterns,
+    guard,
+    bound_vars,
+  }
+}
+
+impl Pattern {
+  fn to_alternative(&self, item: Vec<Stmt>, symbol_table: &SymbolTable) -> Alternative {
+    let s = self.to_subpattern(symbol_table);
+    Alternative {
+      tag: s.tag,
+      subpatterns: s.subpatterns,
+      bound_vars: s.bound_vars,
+      guard: s.guard,
+      item
+    }
+  }
+
+  fn to_subpattern(&self, symbol_table: &SymbolTable) -> Subpattern {
+    use self::Pattern::*;
+    match self {
+      TupleStruct(name, inner_patterns) => {
+        let symbol = symbol_table.lookup_by_name(name).expect(&format!("Symbol {} not found", name));
+        handle_symbol(Some(symbol), inner_patterns, symbol_table)
+      },
+      TuplePattern(inner_patterns) => handle_symbol(None, inner_patterns, symbol_table),
+      Record(_name, _pairs) => {
+        unimplemented!()
+      },
+      Ignored => Subpattern { tag: None, subpatterns: vec![], guard: None, bound_vars: vec![] },
+      Literal(lit) => lit.to_subpattern(symbol_table),
+    }
+  }
+}
+
+impl PatternLiteral {
+  fn to_subpattern(&self, symbol_table: &SymbolTable) -> Subpattern {
+    use self::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),
+          _ => panic!("This should never happen")
+        });
+        let guard = Some(Expr::Call {
+          f: Box::new(Expr::Func(Func::BuiltIn(Rc::new("==".to_string())))),
+          args: vec![comparison, Expr::ConditionalTargetSigilValue],
+        });
+        Subpattern {
+          tag: None,
+          subpatterns: vec![],
+          guard,
+          bound_vars: vec![],
+        }
+      },
+      StringPattern(s) => {
+        let guard = Some(Expr::Call {
+          f: Box::new(Expr::Func(Func::BuiltIn(Rc::new("==".to_string())))),
+          args: vec![Expr::Lit(Lit::StringLit(s.clone())), Expr::ConditionalTargetSigilValue]
+        });
+
+        Subpattern {
+          tag: None,
+          subpatterns: vec![],
+          guard,
+          bound_vars: vec![],
+        }
+      },
+      BoolPattern(b) =>  {
+        let guard = Some(if *b {
+          Expr::ConditionalTargetSigilValue
+        } else {
+          Expr::Call {
+            f: Box::new(Expr::Func(Func::BuiltIn(Rc::new("!".to_string())))),
+            args: vec![Expr::ConditionalTargetSigilValue]
+          }
+        });
+        Subpattern {
+          tag: None,
+          subpatterns: vec![],
+          guard,
+          bound_vars: vec![],
+        }
+      },
+      VarPattern(var) => match symbol_table.lookup_by_name(var) {
+        Some(symbol) => handle_symbol(Some(symbol), &vec![], symbol_table),
+        None => Subpattern {
+          tag: None,
+          subpatterns: vec![],
+          guard: None,
+          bound_vars: vec![Some(var.clone())],
+        }
+      }
+    }
+  }
+}
+
+impl Declaration {
+  fn reduce(&self, symbol_table: &SymbolTable) -> Stmt {
+    use self::Declaration::*;
+    use ::ast::Signature;
+    match self {
+      Binding {name, constant, expr } => Stmt::Binding { name: name.clone(), constant: *constant, expr: expr.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(),
+          body: statements.iter().map(|stmt| stmt.reduce(symbol_table)).collect(),
+        }
+      },
+      TypeDecl { .. } => Stmt::Noop,
+      TypeAlias(_, _) => Stmt::Noop,
+      Interface { .. } => Stmt::Noop,
+      Impl { .. } => Stmt::Expr(Expr::UnimplementedSigilValue),
+      _ => Stmt::Expr(Expr::UnimplementedSigilValue)
+    }
+  }
+}
+
+impl BinOp {
+  fn reduce(&self, symbol_table: &SymbolTable, lhs: &Box<Expression>, rhs: &Box<Expression>) -> Expr {
+    if **self.sigil() == "=" {
+      Expr::Assign {
+        val: Box::new(lhs.reduce(symbol_table)),
+        expr: Box::new(rhs.reduce(symbol_table)),
+      }
+    } else {
+      let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
+      Expr::Call { f, args: vec![lhs.reduce(symbol_table), rhs.reduce(symbol_table)]}
+    }
+  }
+}
+
+impl PrefixOp {
+  fn reduce(&self, symbol_table: &SymbolTable, arg: &Box<Expression>) -> Expr {
+    let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
+    Expr::Call { f, args: vec![arg.reduce(symbol_table)]}
+  }
+}

schala-lang/language/src/source_map.rs

@@ -0,0 +1,27 @@
+
+#[derive(Debug, Clone)]
+pub struct SourceMap<T> {
+  pub node: T,
+  pub data: Option<SourceData>
+}
+
+impl<T> SourceMap<T> {
+  pub fn get(&self) -> &T {
+    &self.node
+  }
+
+  /*
+  pub fn get_source_data(&self) -> Option<SourceData> {
+    self.data.clone()
+  }
+  */
+}
+
+#[derive(Debug, Clone)]
+pub struct SourceData {
+  pub line_number: usize,
+  pub char_idx: usize
+}
+
+
+

schala-lang/language/src/symbol_table.rs

@@ -11,10 +11,16 @@ pub struct SymbolTable {
   pub values: HashMap<Rc<String>, Symbol> //TODO this will eventually have real type information
 }
 
+//TODO add various types of lookups here, maybe multiple hash tables internally? also make values
+//non-public
 impl SymbolTable {
   pub fn new() -> SymbolTable {
     SymbolTable { values: HashMap::new() }
   }
+
+  pub fn lookup_by_name(&self, name: &Rc<String>) -> Option<&Symbol> {
+    self.values.get(name)
+  }
 }
 
 #[derive(Debug)]
@@ -33,6 +39,7 @@ impl fmt::Display for Symbol {
 pub enum SymbolSpec {
   Func(Vec<TypeName>),
   DataConstructor {
+    index: usize,
     type_name: Rc<String>,
     type_args: Vec<Rc<String>>,
   },
@@ -43,7 +50,7 @@ impl fmt::Display for SymbolSpec {
     use self::SymbolSpec::*;
     match self {
       Func(type_names) => write!(f, "Func({:?})", type_names),
-      DataConstructor { type_name, type_args } => write!(f, "DataConstructor({:?} -> {})", type_args, type_name),
+      DataConstructor { index, type_name, type_args } => write!(f, "DataConstructor(idx: {})({:?} -> {})", index, type_args, type_name),
     }
   }
 }
@@ -52,7 +59,7 @@ 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, TypeName, Variant, TypeSingletonName, TypeBody};
+    use self::ast::{Statement, TypeIdentifier, Variant, TypeSingletonName, TypeBody};
     use self::ast::Declaration::*;
     for statement in ast.0.iter() {
       if let Statement::Declaration(decl) = statement {
@@ -62,7 +69,7 @@ impl SymbolTable {
             let mut types = vec![];
             for param in signature.params.iter() {
               match param {
-                (_, Some(ty)) => {
+                (_, Some(_ty)) => {
                   //TODO eventually handle this case different
                   types.push(Rc::new(format!("{}", ch)));
                   ch = ((ch as u8) + 1) as char;
@@ -79,11 +86,13 @@ impl SymbolTable {
               Symbol { name: signature.name.clone(), spec }
               );
           },
-          TypeDecl { name: TypeSingletonName { name, params}, body: TypeBody(variants), mutable } => {
-            for var in variants {
+          //TODO figure out why _params isn't being used here
+          TypeDecl { name: TypeSingletonName { name, params: _params}, body: TypeBody(variants), mutable: _mutable, } => {
+            for (index, var) in variants.iter().enumerate() {
               match var {
                 Variant::UnitStruct(variant_name) => {
                   let spec = SymbolSpec::DataConstructor {
+                    index,
                     type_name: name.clone(),
                     type_args: vec![],
                   };
@@ -91,10 +100,11 @@ impl SymbolTable {
                 },
                 Variant::TupleStruct(variant_name, tuple_members) => {
                   let type_args = tuple_members.iter().map(|type_name| match type_name {
-                    TypeName::Singleton(TypeSingletonName { name, ..}) => name.clone(),
-                    TypeName::Tuple(_) => unimplemented!(),
+                    TypeIdentifier::Singleton(TypeSingletonName { name, ..}) => name.clone(),
+                    TypeIdentifier::Tuple(_) => unimplemented!(),
                   }).collect();
-                  let spec = SymbolSpec::DataConstructor { 
+                  let spec = SymbolSpec::DataConstructor {
+                    index,
                     type_name: name.clone(),
                     type_args
                   };

schala-lang/language/src/tokenizing.rs

@@ -5,14 +5,14 @@ use std::iter::{Iterator, Peekable};
 use std::fmt;
 
 #[derive(Debug, PartialEq, Clone)]
-pub enum TokenType {
+pub enum TokenKind {
   Newline, Semicolon,
 
   LParen, RParen,
   LSquareBracket, RSquareBracket,
   LAngleBracket, RAngleBracket,
   LCurlyBrace, RCurlyBrace,
-  Pipe,
+  Pipe, Backslash,
 
   Comma, Period, Colon, Underscore,
   Slash,
@@ -27,9 +27,9 @@ pub enum TokenType {
 
   Error(String),
 }
-use self::TokenType::*;
+use self::TokenKind::*;
 
-impl fmt::Display for TokenType {
+impl fmt::Display for TokenKind {
   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
     match self {
       &Operator(ref s) => write!(f, "Operator({})", **s),
@@ -49,7 +49,6 @@ pub enum Kw {
   Is,
   Func,
   For, While,
-  Match,
   Const, Let, In,
   Mut,
   Return,
@@ -88,19 +87,28 @@ lazy_static! {
 
 #[derive(Debug, Clone)]
 pub struct Token {
-  pub token_type: TokenType,
+  pub kind: TokenKind,
   pub offset: (usize, usize),
 }
 
+#[derive(Debug, Clone)]
+pub struct TokenMetadata {
+  pub offset: (usize, usize)
+}
+
 impl Token {
   pub fn get_error(&self) -> Option<String> {
-    match self.token_type {
-      TokenType::Error(ref s) => Some(s.clone()),
+    match self.kind {
+      TokenKind::Error(ref s) => Some(s.clone()),
       _ => None,
     }
   }
   pub fn to_string_with_metadata(&self) -> String {
-    format!("{}(L:{},c:{})", self.token_type, self.offset.0, self.offset.1)
+    format!("{}(L:{},c:{})", self.kind, self.offset.0, self.offset.1)
+  }
+
+  pub fn get_kind(&self) -> TokenKind {
+    self.kind.clone()
   }
 }
 
@@ -122,7 +130,7 @@ pub fn tokenize(input: &str) -> Vec<Token> {
       .peekable();
 
   while let Some((line_idx, ch_idx, c)) = input.next() {
-    let cur_tok_type = match c {
+    let cur_tok_kind = match c {
       '/' => match input.peek().map(|t| t.2) {
         Some('/') => {
           while let Some((_, _, c)) = input.next() {
@@ -158,17 +166,18 @@ pub fn tokenize(input: &str) -> Vec<Token> {
       '{' => LCurlyBrace, '}' => RCurlyBrace,
       '[' => LSquareBracket, ']' => RSquareBracket,
       '"' => handle_quote(&mut input),
+      '\\' => Backslash,
       c if c.is_digit(10) => handle_digit(c, &mut input),
       c if c.is_alphabetic() || c == '_' => handle_alphabetic(c, &mut input), //TODO I'll probably have to rewrite this if I care about types being uppercase, also type parameterization
       c if is_operator(&c) => handle_operator(c, &mut input),
       unknown => Error(format!("Unexpected character: {}", unknown)),
     };
-    tokens.push(Token { token_type: cur_tok_type, offset: (line_idx, ch_idx) });
+    tokens.push(Token { kind: cur_tok_kind, offset: (line_idx, ch_idx) });
   }
   tokens
 }
 
-fn handle_digit(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+fn handle_digit(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenKind {
   if c == '0' && input.peek().map_or(false, |&(_, _, c)| { c == 'x' }) {
     input.next();
     let rest: String = input.peeking_take_while(|&(_, _, ref c)| c.is_digit(16) || *c == '_').map(|(_, _, c)| { c }).collect();
@@ -183,7 +192,7 @@ fn handle_digit(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) ->
   }
 }
 
-fn handle_quote(input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+fn handle_quote(input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenKind {
   let mut buf = String::new();
   loop {
     match input.next().map(|(_, _, c)| { c }) {
@@ -202,22 +211,22 @@ fn handle_quote(input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType
         }
       },
       Some(c) => buf.push(c),
-      None => return TokenType::Error(format!("Unclosed string")),
+      None => return TokenKind::Error(format!("Unclosed string")),
     }
   }
-  TokenType::StrLiteral(Rc::new(buf))
+  TokenKind::StrLiteral(Rc::new(buf))
 }
 
-fn handle_alphabetic(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+fn handle_alphabetic(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenKind {
   let mut buf = String::new();
   buf.push(c);
   if c == '_' && input.peek().map(|&(_, _, c)| { !c.is_alphabetic() }).unwrap_or(true) {
-    return TokenType::Underscore
+    return TokenKind::Underscore
   }
 
   loop {
     match input.peek().map(|&(_, _, c)| { c }) {
-      Some(c) if c.is_alphanumeric() => {
+      Some(c) if c.is_alphanumeric() || c == '_' => {
         input.next();
         buf.push(c);
       },
@@ -226,12 +235,12 @@ fn handle_alphabetic(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>
   }
 
   match KEYWORDS.get(buf.as_str()) {
-    Some(kw) => TokenType::Keyword(*kw),
-    None => TokenType::Identifier(Rc::new(buf)),
+    Some(kw) => TokenKind::Keyword(*kw),
+    None => TokenKind::Identifier(Rc::new(buf)),
   }
 }
 
-fn handle_operator(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+fn handle_operator(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenKind {
   match c {
     '<' | '>' | '|' | '.' => {
       let ref next = input.peek().map(|&(_, _, c)| { c });
@@ -276,7 +285,7 @@ fn handle_operator(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>)
       }
     }
   }
-  TokenType::Operator(Rc::new(buf))
+  TokenKind::Operator(Rc::new(buf))
 }
 
 #[cfg(test)]
@@ -291,26 +300,29 @@ mod schala_tokenizer_tests {
   #[test]
   fn tokens() {
     let a = tokenize("let a: A<B> = c ++ d");
-    let token_types: Vec<TokenType> = a.into_iter().map(move |t| t.token_type).collect();
-    assert_eq!(token_types, vec![Keyword(Let), ident!("a"), Colon, ident!("A"),
+    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")]);
   }
 
   #[test]
   fn underscores() {
-    let token_types: Vec<TokenType> = tokenize("4_8").into_iter().map(move |t| t.token_type).collect();
-    assert_eq!(token_types, vec![digit!("4"), Underscore, digit!("8")]);
+    let token_kinds: Vec<TokenKind> = tokenize("4_8").into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds, vec![digit!("4"), Underscore, digit!("8")]);
+
+    let token_kinds2: Vec<TokenKind> = tokenize("aba_yo").into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds2, vec![ident!("aba_yo")]);
   }
 
   #[test]
   fn comments() {
-    let token_types: Vec<TokenType> = tokenize("1  + /* hella /* bro */ */ 2").into_iter().map(move |t| t.token_type).collect();
-    assert_eq!(token_types, vec![digit!("1"), op!("+"), digit!("2")]);
+    let token_kinds: Vec<TokenKind> = tokenize("1  + /* hella /* bro */ */ 2").into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds, vec![digit!("1"), op!("+"), digit!("2")]);
   }
 
   #[test]
   fn backtick_operators() {
-    let token_types: Vec<TokenType> = tokenize("1 `plus` 2").into_iter().map(move |t| t.token_type).collect();
-    assert_eq!(token_types, vec![digit!("1"), op!("plus"), digit!("2")]);
+    let token_kinds: Vec<TokenKind> = tokenize("1 `plus` 2").into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds, vec![digit!("1"), op!("plus"), digit!("2")]);
   }
 }

schala-lang/language/src/typechecking.rs

@@ -0,0 +1,254 @@
+use std::rc::Rc;
+
+use ast::*;
+use util::ScopeStack;
+
+pub type TypeName = Rc<String>;
+
+pub struct TypeContext<'a> {
+  variable_map: ScopeStack<'a, Rc<String>, Type<TVar>>,
+  evar_count: u32
+}
+
+/// `InferResult` is the monad in which type inference takes place.
+type InferResult<T> = Result<T, TypeError>;
+
+#[derive(Debug, Clone)]
+struct TypeError { msg: String }
+
+impl TypeError {
+  fn new<A>(msg: &str) -> InferResult<A> {
+    Err(TypeError { msg: msg.to_string() })
+  }
+}
+
+/// `Type` is parameterized by whether the type variables can be just universal, or universal or
+/// existential.
+#[derive(Debug, Clone)]
+enum Type<A> {
+  Var(A),
+  Const(TConst),
+  Arrow(Box<Type<A>>, Box<Type<A>>),
+}
+
+#[derive(Debug, Clone)]
+enum TVar {
+  Univ(UVar),
+  Exist(ExistentialVar)
+}
+
+#[derive(Debug, Clone)]
+struct UVar(Rc<String>);
+
+#[derive(Debug, Clone)]
+struct ExistentialVar(u32);
+
+impl Type<UVar> {
+  fn to_tvar(&self) -> Type<TVar> {
+    match self {
+      Type::Var(UVar(name)) => Type::Var(TVar::Univ(UVar(name.clone()))),
+      Type::Const(ref c) => Type::Const(c.clone()),
+      Type::Arrow(a, b) => Type::Arrow(
+        Box::new(a.to_tvar()),
+        Box::new(b.to_tvar())
+      )
+    }
+  }
+}
+
+impl Type<TVar> {
+  fn skolemize(&self) -> Type<UVar> {
+    match self {
+      Type::Var(TVar::Univ(uvar)) => Type::Var(uvar.clone()),
+      Type::Var(TVar::Exist(_)) => Type::Var(UVar(Rc::new(format!("sk")))),
+      Type::Const(ref c) => Type::Const(c.clone()),
+      Type::Arrow(a, b) => Type::Arrow(
+        Box::new(a.skolemize()),
+        Box::new(b.skolemize())
+      )
+    }
+  }
+}
+
+impl TypeIdentifier {
+  fn to_monotype(&self) -> Type<UVar> {
+    match self {
+      TypeIdentifier::Tuple(_) => Type::Const(TConst::Nat),
+      TypeIdentifier::Singleton(TypeSingletonName { name, .. }) => {
+        match &name[..] {
+          "Nat" => Type::Const(TConst::Nat),
+          "Int" => Type::Const(TConst::Int),
+          "Float" => Type::Const(TConst::Float),
+          "Bool" => Type::Const(TConst::Bool),
+          "String" => Type::Const(TConst::StringT),
+          _ => Type::Const(TConst::Nat),
+        }
+      }
+    }
+  }
+}
+
+#[derive(Debug, Clone)]
+enum TConst {
+  User(Rc<String>),
+  Unit,
+  Nat,
+  Int,
+  Float,
+  StringT,
+  Bool,
+}
+
+impl TConst {
+  fn user(name: &str) -> 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
+    }
+  }
+
+  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))
+    }
+  }
+}
+
+impl<'a> TypeContext<'a> {
+  fn infer_ast(&mut self, ast: &AST) -> InferResult<Type<UVar>> {
+    self.infer_block(&ast.0)
+  }
+
+  fn infer_statement(&mut self, stmt: &Statement) -> InferResult<Type<UVar>> {
+    match stmt {
+      Statement::ExpressionStatement(ref expr) => self.infer_expr(expr),
+      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))
+        }
+      },
+      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])?; // 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"))
+    })
+  }
+
+  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")
+  }
+
+  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)?;
+    }
+    Ok(output)
+  }
+
+  fn unify(&mut self, _t1: &Type<TVar>, _t2: &Type<TVar>) -> InferResult<Type<TVar>> {
+    TypeError::new("not implemented")
+  }
+
+  fn allocate_existential(&mut self) -> Type<TVar> {
+    let n = self.evar_count;
+    self.evar_count += 1;
+    Type::Var(TVar::Exist(ExistentialVar(n)))
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  fn parse(input: &str) -> AST {
+    let tokens: Vec<::tokenizing::Token> = ::tokenizing::tokenize(input);
+    let mut parser = ::parsing::Parser::new(tokens);
+    parser.parse().unwrap()
+  }
+
+  macro_rules! type_test {
+    ($input:expr, $correct:expr) => {
+      {
+      let mut tc = TypeContext::new();
+      let ast = parse($input);
+      tc.add_symbols(&ast);
+      assert_eq!($correct, tc.type_check(&ast).unwrap())
+      }
+    }
+  }
+
+
+
+  #[test]
+  fn basic_inference() {
+
+  }
+}

schala-lang/language/src/util.rs

@@ -2,17 +2,16 @@ use std::collections::HashMap;
 use std::hash::Hash;
 use std::cmp::Eq;
 
-//TODO rename this ScopeStack
 #[derive(Default, Debug)]
-pub struct StateStack<'a, T: 'a, V: 'a>  where T: Hash + Eq {
-  parent: Option<&'a StateStack<'a, T, V>>,
+pub struct ScopeStack<'a, T: 'a, V: 'a>  where T: Hash + Eq {
+  parent: Option<&'a ScopeStack<'a, T, V>>,
   values: HashMap<T, V>,
   scope_name: Option<String>
 }
 
-impl<'a, T, V> StateStack<'a, T, V> where T: Hash + Eq {
-  pub fn new(name: Option<String>) -> StateStack<'a, T, V> where T: Hash + Eq {
-    StateStack {
+impl<'a, T, V> ScopeStack<'a, T, V> where T: Hash + Eq {
+  pub fn new(name: Option<String>) -> ScopeStack<'a, T, V> where T: Hash + Eq {
+    ScopeStack {
       parent: None,
       values: HashMap::new(),
       scope_name: name
@@ -28,14 +27,15 @@ impl<'a, T, V> StateStack<'a, T, V> where T: Hash + Eq {
       (Some(value), _) => Some(value),
     }
   }
-  //TODO rename new_scope
-  pub fn new_frame(&'a self, name: Option<String>) -> StateStack<'a, T, V> where T: Hash + Eq {
-    StateStack {
+
+  pub fn new_scope(&'a self, name: Option<String>) -> ScopeStack<'a, T, V> where T: Hash + Eq {
+    ScopeStack {
       parent: Some(self),
       values: HashMap::default(),
       scope_name: name,
     }
   }
+  #[allow(dead_code)]
   pub fn get_name(&self) -> Option<&String> {
     self.scope_name.as_ref()
   }

schala-lang/src/eval.rs

@@ -1,375 +0,0 @@
-use std::cell::RefCell;
-use std::rc::Rc;
-use std::fmt::Write;
-use std::io;
-
-use itertools::Itertools;
-
-use util::StateStack;
-use reduced_ast::{ReducedAST, Stmt, Expr, Lit, Func};
-use symbol_table::{SymbolSpec, Symbol, SymbolTable};
-
-pub struct State<'a> {
-  values: StateStack<'a, Rc<String>, ValueEntry>,
-  symbol_table_handle: Rc<RefCell<SymbolTable>>,
-}
-
-macro_rules! builtin_binding {
-  ($name:expr, $values:expr) => {
-    $values.insert(Rc::new(format!($name)), ValueEntry::Binding { constant: true, val: Expr::Func(Func::BuiltIn(Rc::new(format!($name)))) });
-  }
-}
-
-impl<'a> State<'a> {
-  pub fn new(symbol_table_handle: Rc<RefCell<SymbolTable>>) -> State<'a> {
-    let mut values = StateStack::new(Some(format!("global")));
-    builtin_binding!("print", values);
-    builtin_binding!("println", values);
-    builtin_binding!("getline", values);
-    State { values, symbol_table_handle }
-  }
-
-  pub fn debug_print(&self) -> String {
-    format!("Values: {:?}", self.values)
-  }
-}
-
-#[derive(Debug)]
-enum ValueEntry {
-  Binding {
-    constant: bool,
-    val: /*FullyEvaluatedExpr*/ Expr,
-  }
-}
-
-type EvalResult<T> = Result<T, String>;
-
-
-impl Expr {
-  fn to_repl(&self) -> String {
-    use self::Lit::*;
-    use self::Func::*;
-    fn paren_wrapped_vec(exprs: &Vec<Expr>) -> String {
-      let mut buf = String::new();
-      write!(buf, "(").unwrap();
-      for term in exprs.iter().map(|e| Some(e)).intersperse(None) {
-        match term {
-          Some(e) => write!(buf, "{}", e.to_repl()).unwrap(),
-          None => write!(buf, ", ").unwrap(),
-        };
-      }
-      write!(buf, ")").unwrap();
-      buf
-    }
-
-    match self {
-      Expr::Lit(ref l) => match l {
-        Nat(n) => format!("{}", n),
-        Int(i) => format!("{}", i),
-        Float(f) => format!("{}", f),
-        Bool(b) => format!("{}", b),
-        StringLit(s) => format!("\"{}\"", s),
-        Custom(name, args) if args.len() == 0 => format!("{}", name),
-        Custom(name, args) => format!("{}{}", name, paren_wrapped_vec(args)),
-      },
-      Expr::Func(f) => match f {
-        BuiltIn(name) => format!("<built-in function {}>", name),
-        UserDefined { name: None, .. } => format!("<function>"),
-        UserDefined { name: Some(name), .. } => format!("<function {}>", name),
-      },
-      Expr::Constructor { name } => format!("<constructor {}>", name),
-      Expr::Tuple(exprs) => paren_wrapped_vec(exprs),
-      _ => format!("{:?}", self),
-    }
-  }
-}
-
-impl<'a> State<'a> {
-  pub fn evaluate(&mut self, ast: ReducedAST, repl: bool) -> Vec<Result<String, String>> {
-    let mut acc = vec![];
-
-    // handle prebindings
-    for statement in ast.0.iter() {
-      self.prebinding(statement);
-    }
-
-    for statement in ast.0 {
-      match self.statement(statement) {
-        Ok(Some(ref output)) if repl => acc.push(Ok(output.to_repl())),
-        Ok(_) => (),
-        Err(error) => {
-          acc.push(Err(format!("Runtime error: {}", error)));
-          return acc;
-        },
-      }
-    }
-    acc
-  }
-
-  fn prebinding(&mut self, stmt: &Stmt) {
-    match stmt {
-      Stmt::PreBinding { name, func } => {
-        let v_entry = ValueEntry::Binding { constant: true, val: Expr::Func(func.clone()) };
-        self.values.insert(name.clone(), v_entry);
-      },
-      Stmt::Expr(_expr) => {
-        //TODO have this support things like nested function defs
-
-      },
-      _ => ()
-    }
-  }
-
-  fn statement(&mut self, stmt: Stmt) -> EvalResult<Option<Expr>> {
-    match stmt {
-      Stmt::Binding { name, constant, expr } => {
-        let val = self.expression(expr)?;
-        self.values.insert(name.clone(), ValueEntry::Binding { constant, val });
-        Ok(None)
-      },
-      Stmt::Expr(expr) => Ok(Some(self.expression(expr)?)),
-      Stmt::PreBinding {..} | Stmt::Noop => Ok(None),
-    }
-  }
-
-  fn block(&mut self, stmts: Vec<Stmt>) -> EvalResult<Expr> {
-    let mut ret = None;
-    for stmt in stmts {
-      ret = self.statement(stmt)?;
-    }
-    Ok(ret.unwrap_or(Expr::Unit))
-  }
-
-  fn expression(&mut self, expr: Expr) -> EvalResult<Expr> {
-    use self::Expr::*;
-    match expr {
-      literal @ Lit(_) => Ok(literal),
-      Call { box f, args } => {
-        match self.expression(f)? {
-          Constructor {name} => self.apply_data_constructor(name, args),
-          Func(f) => self.apply_function(f, args),
-          other => return Err(format!("Tried to call {:?} which is not a function or data constructor", other)),
-        }
-      },
-      Val(v) => self.value(v),
-      constr @ Constructor { .. } => Ok(constr),
-      func @ Func(_) => Ok(func),
-      Tuple(exprs) => Ok(Tuple(exprs.into_iter().map(|expr| self.expression(expr)).collect::<Result<Vec<Expr>,_>>()?)),
-      Conditional { box cond, then_clause, else_clause } => self.conditional(cond, then_clause, else_clause),
-      Assign { box val, box expr } => {
-        let name = match val  {
-          Expr::Val(name) => name,
-          _ => return Err(format!("Trying to assign to a non-value")),
-        };
-
-        let constant = match self.values.lookup(&name) {
-          None => return Err(format!("{} is undefined", name)),
-          Some(ValueEntry::Binding { constant, .. }) => constant.clone(),
-        };
-        if constant {
-          return Err(format!("trying to update {}, a non-mutable binding", name));
-        }
-        let val = self.expression(expr)?;
-        self.values.insert(name.clone(), ValueEntry::Binding { constant: false, val });
-        Ok(Expr::Unit)
-      },
-      e => Err(format!("Expr {:?} eval not implemented", e))
-    }
-  }
-
-  fn apply_data_constructor(&mut self, name: Rc<String>, args: Vec<Expr>) -> EvalResult<Expr> {
-    {
-      let symbol_table = self.symbol_table_handle.borrow();
-      match symbol_table.values.get(&name) {
-        Some(Symbol { spec: SymbolSpec::DataConstructor { type_name, type_args }, name }) => {
-          if args.len() != type_args.len() {
-            return Err(format!("Data constructor {} requires {} args", name, type_args.len()));
-          }
-          ()
-        },
-        _ => return Err(format!("Bad symbol {}", name))
-      }
-    }
-    let evaled_args = args.into_iter().map(|expr| self.expression(expr)).collect::<Result<Vec<Expr>,_>>()?;
-    //let evaled_args = vec![];
-    Ok(Expr::Lit(self::Lit::Custom(name.clone(), evaled_args)))
-  }
-
-  fn apply_function(&mut self, f: Func, args: Vec<Expr>) -> EvalResult<Expr> {
-    match f {
-      Func::BuiltIn(sigil) => self.apply_builtin(sigil, args),
-      Func::UserDefined { params, body, name } => {
-
-        if params.len() != args.len() {
-          return Err(format!("calling a {}-argument function with {} args", params.len(), args.len()))
-        }
-        let mut func_state = State {
-          values: self.values.new_frame(name.map(|n| format!("{}", n))),
-          symbol_table_handle: self.symbol_table_handle.clone(),
-        };
-        for (param, val) in params.into_iter().zip(args.into_iter()) {
-          let val = func_state.expression(val)?;
-          func_state.values.insert(param, ValueEntry::Binding { constant: true, val });
-        }
-        // TODO figure out function return semantics
-        func_state.block(body)
-      }
-    }
-  }
-
-  fn apply_builtin(&mut self, name: Rc<String>, args: Vec<Expr>) -> EvalResult<Expr> {
-    use self::Expr::*;
-    use self::Lit::*;
-    let evaled_args: Result<Vec<Expr>, String> = args.into_iter().map(|arg| self.expression(arg)).collect();
-    let evaled_args = evaled_args?;
-
-    Ok(match (name.as_str(), evaled_args.as_slice()) {
-      /* binops */
-      ("+", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l + r)),
-      ("++", &[Lit(StringLit(ref s1)), Lit(StringLit(ref s2))]) => Lit(StringLit(Rc::new(format!("{}{}", s1, s2)))),
-      ("-", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l - r)),
-      ("*", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l * r)),
-      ("/", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Float((l as f64)/ (r as f64))),
-      ("//", &[Lit(Nat(l)), Lit(Nat(r))]) => if r == 0 {
-        return Err(format!("divide by zero"));
-      } else {
-        Lit(Nat(l / r))
-      },
-      ("%", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l % r)),
-      ("^", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l ^ r)),
-      ("&", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l & r)),
-      ("|", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l | r)),
-
-      ("==", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l == r)),
-      ("==", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l == r)),
-      ("==", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l == r)),
-      ("==", &[Lit(Bool(l)), Lit(Bool(r))]) => Lit(Bool(l == r)),
-      ("==", &[Lit(StringLit(ref l)), Lit(StringLit(ref r))]) => Lit(Bool(l == r)),
-
-      /* prefix ops */
-      ("!", &[Lit(Bool(true))]) => Lit(Bool(false)),
-      ("!", &[Lit(Bool(false))]) => Lit(Bool(true)),
-      ("-", &[Lit(Nat(n))]) => Lit(Int(-1*(n as i64))),
-      ("-", &[Lit(Int(n))]) => Lit(Int(-1*(n as i64))),
-      ("+", &[Lit(Int(n))]) => Lit(Int(n)),
-      ("+", &[Lit(Nat(n))]) => Lit(Nat(n)),
-
-
-      /* builtin functions */
-      ("print", &[ref anything]) => {
-        print!("{}", anything.to_repl());
-        Expr::Unit
-      },
-      ("println", &[ref anything]) => {
-        println!("{}", anything.to_repl());
-        Expr::Unit
-      },
-      ("getline", &[]) => {
-        let mut buf = String::new();
-        io::stdin().read_line(&mut buf).expect("Error readling line in 'getline'");
-        Lit(StringLit(Rc::new(buf.trim().to_string())))
-      },
-      (x, args) => return Err(format!("bad or unimplemented builtin {:?} | {:?}", x, args)),
-    })
-  }
-
-  fn conditional(&mut self, cond: Expr, then_clause: Vec<Stmt>, else_clause: Vec<Stmt>) -> EvalResult<Expr> {
-    let cond = self.expression(cond)?;
-    Ok(match cond {
-      Expr::Lit(Lit::Bool(true)) =>  self.block(then_clause)?,
-      Expr::Lit(Lit::Bool(false)) => self.block(else_clause)?,
-      _ => return Err(format!("Conditional with non-boolean condition"))
-    })
-  }
-
-  fn value(&mut self, name: Rc<String>) -> EvalResult<Expr> {
-    use self::ValueEntry::*;
-    use self::Func::*;
-    //TODO add a layer of indirection here to talk to the symbol table first, and only then look up
-    //in the values table
-
-    let symbol_table = self.symbol_table_handle.borrow();
-    let value = symbol_table.values.get(&name);
-    Ok(match value {
-      Some(Symbol { name, spec }) => match spec {
-        SymbolSpec::DataConstructor { type_name, type_args } => {
-          if type_args.len() == 0 {
-            Expr::Lit(Lit::Custom(name.clone(), vec![]))
-          } else {
-            return Err(format!("This data constructor thing not done"))
-          }
-        },
-        SymbolSpec::Func(_) => match self.values.lookup(&name) {
-          Some(Binding { val: Expr::Func(UserDefined { name, params, body }), .. }) => {
-            Expr::Func(UserDefined { name: name.clone(), params: params.clone(), body: body.clone() })
-          },
-          _ => unreachable!(),
-        },
-      },
-      /* see if it's an ordinary variable TODO make variables go in symbol table */
-      None => match self.values.lookup(&name) {
-        Some(Binding { val, .. }) => val.clone(),
-        None => return Err(format!("Couldn't find value {}", name)),
-      }
-    })
-  }
-}
-
-#[cfg(test)]
-mod eval_tests {
-  use std::cell::RefCell;
-  use std::rc::Rc;
-  use symbol_table::SymbolTable;
-  use tokenizing::tokenize;
-  use parsing::parse;
-  use eval::State;
-
-  macro_rules! fresh_env {
-    ($string:expr, $correct:expr) => {
-      let symbol_table = Rc::new(RefCell::new(SymbolTable::new()));
-      let mut state = State::new(symbol_table);
-      let ast = parse(tokenize($string)).0.unwrap();
-      state.symbol_table_handle.borrow_mut().add_top_level_symbols(&ast);
-      let reduced = ast.reduce(&state.symbol_table_handle.borrow());
-      let all_output = state.evaluate(reduced, true);
-      let ref output = all_output.last().unwrap();
-      assert_eq!(**output, Ok($correct.to_string()));
-    }
-  }
-
-  #[test]
-  fn test_basic_eval() {
-    fresh_env!("1 + 2", "3");
-    fresh_env!("let mut a = 1; a = 2", "Unit");
-    fresh_env!("let mut a = 1; a = 2; a", "2");
-    fresh_env!(r#"("a", 1 + 2)"#, r#"("a", 3)"#);
-  }
-
-  #[test]
-  fn function_eval() {
-    fresh_env!("fn oi(x) { x + 1 }; oi(4)", "5");
-    fresh_env!("fn oi(x) { x + 1 }; oi(1+2)", "4");
-  }
-
-  #[test]
-  fn scopes() {
-    let scope_ok = r#"
-    let a = 20
-    fn haha() {
-      let a = 10
-      a
-    }
-    haha()
-    "#;
-    fresh_env!(scope_ok, "10");
-    let scope_ok = r#"
-    let a = 20
-    fn haha() {
-      let a = 10
-      a
-    }
-    a
-    "#;
-    fresh_env!(scope_ok, "20");
-  }
-}

schala-lang/src/reduced_ast.rs

@@ -1,199 +0,0 @@
-use std::rc::Rc;
-
-use ast::{AST, Statement, Expression, Declaration, Discriminator, IfExpressionBody, Pattern};
-use symbol_table::{Symbol, SymbolSpec, SymbolTable};
-use builtin::{BinOp, PrefixOp};
-
-#[derive(Debug)]
-pub struct ReducedAST(pub Vec<Stmt>);
-
-#[derive(Debug, Clone)]
-pub enum Stmt {
-  PreBinding {
-    name: Rc<String>,
-    func: Func,
-  },
-  Binding {
-    name: Rc<String>,
-    constant: bool,
-    expr: Expr,
-  },
-  Expr(Expr),
-  Noop,
-}
-
-#[derive(Debug, Clone)]
-pub enum Expr {
-  Unit,
-  Lit(Lit),
-  Tuple(Vec<Expr>),
-  Func(Func),
-  Val(Rc<String>),
-  Constructor {
-    name: Rc<String>,
-  },
-  Call {
-    f: Box<Expr>,
-    args: Vec<Expr>,
-  },
-  Assign {
-    val: Box<Expr>,
-    expr: Box<Expr>,
-  },
-  Conditional {
-    cond: Box<Expr>,
-    then_clause: Vec<Stmt>,
-    else_clause: Vec<Stmt>,
-  },
-  Match {
-    cond: Box<Expr>,
-    arms: Vec<(Pattern, Vec<Stmt>)>
-  },
-  UnimplementedSigilValue
-}
-
-#[derive(Debug, Clone)]
-pub enum Lit {
-  Nat(u64),
-  Int(i64),
-  Float(f64),
-  Bool(bool),
-  StringLit(Rc<String>),
-  Custom(Rc<String>, Vec<Expr>),
-}
-
-#[derive(Debug, Clone)]
-pub enum Func {
-  BuiltIn(Rc<String>),
-  UserDefined {
-    name: Option<Rc<String>>,
-    params: Vec<Rc<String>>,
-    body: Vec<Stmt>,
-  }
-}
-
-impl AST {
-  pub fn reduce(&self, symbol_table: &SymbolTable) -> ReducedAST {
-    let mut output = vec![];
-    for statement in self.0.iter() {
-      output.push(statement.reduce(symbol_table));
-    }
-    ReducedAST(output)
-  }
-}
-
-impl Statement {
-  fn reduce(&self, symbol_table: &SymbolTable) -> Stmt { 
-    use ast::Statement::*;
-    match self {
-      ExpressionStatement(expr) => Stmt::Expr(expr.reduce(symbol_table)),
-      Declaration(decl) => decl.reduce(symbol_table),
-    }
-  }
-}
-
-impl Expression {
-  fn reduce(&self, symbol_table: &SymbolTable) -> Expr {
-    use ast::ExpressionType::*;
-    let ref input = self.0;
-    match input {
-      NatLiteral(n) => Expr::Lit(Lit::Nat(*n)),
-      FloatLiteral(f) => Expr::Lit(Lit::Float(*f)),
-      StringLiteral(s) => Expr::Lit(Lit::StringLit(s.clone())),
-      BoolLiteral(b) => Expr::Lit(Lit::Bool(*b)),
-      BinExp(binop, lhs, rhs) => binop.reduce(symbol_table, lhs, rhs),
-      PrefixExp(op, arg) => op.reduce(symbol_table, arg),
-      Value(name) => {
-        match symbol_table.values.get(name) {
-          Some(Symbol { spec: SymbolSpec::DataConstructor { type_args, .. }, .. }) => {
-            Expr::Constructor { name: name.clone() }
-          },
-          _ => Expr::Val(name.clone()),
-        }
-      },
-      Call { f, arguments } => Expr::Call {
-        f: Box::new(f.reduce(symbol_table)),
-        args: arguments.iter().map(|arg| arg.reduce(symbol_table)).collect(),
-      },
-      TupleLiteral(exprs) => Expr::Tuple(exprs.iter().map(|e| e.reduce(symbol_table)).collect()),
-      IfExpression { discriminator, body } => reduce_if_expression(discriminator, body, symbol_table),
-      _ => Expr::UnimplementedSigilValue,
-    }
-  }
-}
-
-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),
-    _ => panic!(),
-  });
-  match *body {
-    IfExpressionBody::SimpleConditional(ref then_clause, ref else_clause) => {
-      let then_clause = then_clause.iter().map(|expr| expr.reduce(symbol_table)).collect();
-      let else_clause = match else_clause {
-        None => vec![],
-        Some(stmts) => stmts.iter().map(|expr| expr.reduce(symbol_table)).collect(),
-      };
-      Expr::Conditional { cond, then_clause, else_clause }
-    },
-    IfExpressionBody::SimplePatternMatch(ref pat, ref then_clause, ref else_clause) => {
-      let then_clause = then_clause.iter().map(|expr| expr.reduce(symbol_table)).collect();
-      let else_clause = match else_clause {
-        None => vec![],
-        Some(stmts) => stmts.iter().map(|expr| expr.reduce(symbol_table)).collect(),
-      };
-      Expr::Match {
-        cond,
-        arms: vec![
-          (pat.clone(), then_clause),
-          (Pattern::Ignored, else_clause)
-        ],
-      }
-    },
-    IfExpressionBody::GuardList(ref _guard_arms) => panic!(),
-  }
-}
-
-impl Declaration {
-  fn reduce(&self, symbol_table: &SymbolTable) -> Stmt {
-    use self::Declaration::*;
-    use ::ast::Signature;
-    match self {
-      Binding {name, constant, expr } => Stmt::Binding { name: name.clone(), constant: *constant, expr: expr.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(),
-          body: statements.iter().map(|stmt| stmt.reduce(symbol_table)).collect(),
-        }
-      },
-      TypeDecl { .. } => Stmt::Noop,
-      TypeAlias(_, _) => Stmt::Noop,
-      Interface { .. } => Stmt::Noop,
-      Impl { .. } => Stmt::Expr(Expr::UnimplementedSigilValue),
-      _ => Stmt::Expr(Expr::UnimplementedSigilValue)
-    }
-  }
-}
-
-impl BinOp {
-  fn reduce(&self, symbol_table: &SymbolTable, lhs: &Box<Expression>, rhs: &Box<Expression>) -> Expr {
-    if **self.sigil() == "=" {
-      Expr::Assign {
-        val: Box::new(lhs.reduce(symbol_table)),
-        expr: Box::new(rhs.reduce(symbol_table)),
-      }
-    } else {
-      let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
-      Expr::Call { f, args: vec![lhs.reduce(symbol_table), rhs.reduce(symbol_table)]}
-    }
-  }
-}
-
-impl PrefixOp {
-  fn reduce(&self, symbol_table: &SymbolTable, arg: &Box<Expression>) -> Expr {
-    let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
-    Expr::Call { f, args: vec![arg.reduce(symbol_table)]}
-  }
-}

schala-lang/src/typechecking.rs

@@ -1,493 +0,0 @@
-use std::cell::RefCell;
-use std::rc::Rc;
-use std::collections::HashMap;
-use std::fmt;
-use std::fmt::Write;
-/*
-use std::collections::hash_set::Union;
-use std::iter::Iterator;
-use itertools::Itertools;
-*/
-
-use ast;
-use util::StateStack;
-use symbol_table::{SymbolSpec, SymbolTable};
-
-pub type TypeName = Rc<String>;
-type TypeResult<T> = Result<T, String>;
-
-#[derive(Debug, PartialEq, Clone)]
-enum Type {
-  Const(TConst),
-  Var(TypeName),
-  Func(Vec<Type>),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-enum TConst {
-  Unit,
-  Nat,
-  StringT,
-  Custom(String)
-}
-
-#[derive(Debug, PartialEq, Clone)]
-struct Scheme {
-  names: Vec<TypeName>,
-  ty: Type,
-}
-
-impl fmt::Display for Scheme {
-  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    write!(f, "∀{:?} . {:?}", self.names, self.ty)
-  }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-struct Substitution(HashMap<TypeName, Type>);
-impl Substitution {
-  fn empty() -> Substitution {
-    Substitution(HashMap::new())
-  }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-struct TypeEnv(HashMap<TypeName, Scheme>);
-
-impl TypeEnv {
-  fn default() -> TypeEnv {
-    TypeEnv(HashMap::new())
-  }
-
-  fn populate_from_symbols(&mut self, symbol_table: &SymbolTable) {
-    for (name, symbol) in symbol_table.values.iter() {
-      if let SymbolSpec::Func(ref type_names) = symbol.spec {
-        let mut ch: char = 'a';
-        let mut names = vec![];
-        for _ in type_names.iter() {
-          names.push(Rc::new(format!("{}", ch)));
-          ch = ((ch as u8) + 1) as char;
-        }
-
-        let sigma = Scheme {
-          names: names.clone(),
-          ty: Type::Func(names.into_iter().map(|n| Type::Var(n)).collect())
-        };
-        self.0.insert(name.clone(), sigma);
-      }
-    }
-  }
-}
-
-pub struct TypeContext<'a> {
-  values: StateStack<'a, TypeName, Type>,
-  symbol_table_handle: Rc<RefCell<SymbolTable>>,
-  global_env: TypeEnv
-}
-
-impl<'a> TypeContext<'a> {
-  pub fn new(symbol_table_handle: Rc<RefCell<SymbolTable>>) -> TypeContext<'static> {
-    TypeContext { values: StateStack::new(None), global_env: TypeEnv::default(), symbol_table_handle }
-  }
-
-  pub fn debug_types(&self) -> String {
-    let mut output = format!("Type environment\n");
-    for (name, scheme) in &self.global_env.0 {
-      write!(output, "{} -> {}\n", name, scheme).unwrap();
-    }
-    output
-  }
-
-  pub fn type_check_ast(&mut self, input: &ast::AST) -> Result<String, String> {
-    let ref symbol_table = self.symbol_table_handle.borrow();
-    self.global_env.populate_from_symbols(symbol_table);
-    let output = self.global_env.infer_block(&input.0)?;
-    Ok(format!("{:?}", output))
-  }
-}
-
-impl TypeEnv {
-  fn instantiate(&mut self, sigma: Scheme) -> Type {
-    match sigma {
-      Scheme { ty, .. } => ty,
-    }
-  }
-  fn generate(&mut self, ty: Type) -> Scheme {
-    Scheme {
-      names: vec![], //TODO incomplete
-      ty
-    }
-  }
-  fn infer_block(&mut self, block: &Vec<ast::Statement>) -> TypeResult<Type> {
-    let mut output = Type::Const(TConst::Unit);
-    for statement in block {
-      output = self.infer_statement(statement)?;
-    }
-    Ok(output)
-  }
-  fn infer_statement(&mut self, statement: &ast::Statement) -> TypeResult<Type> {
-    match statement {
-      ast::Statement::ExpressionStatement(expr) => self.infer_expr(expr),
-      ast::Statement::Declaration(decl) => self.infer_decl(decl)
-    }
-  }
-  fn infer_decl(&mut self, decl: &ast::Declaration) -> TypeResult<Type> {
-    use ast::Declaration::*;
-    match decl {
-      Binding { name, expr, .. } => {
-        let ty = self.infer_expr(expr)?;
-        let sigma = self.generate(ty);
-        self.0.insert(name.clone(), sigma);
-      },
-      _ => (),
-    }
-    Ok(Type::Const(TConst::Unit))
-  }
-  fn infer_expr(&mut self, expr: &ast::Expression) -> TypeResult<Type> {
-    match expr {
-      ast::Expression(expr, Some(anno)) => {
-        self.infer_exprtype(expr)
-      },
-      ast::Expression(expr, None) => {
-        self.infer_exprtype(expr)
-      }
-    }
-  }
-
-  fn infer_exprtype(&mut self, expr: &ast::ExpressionType) -> TypeResult<Type> {
-    use self::TConst::*;
-    use ast::ExpressionType::*;
-    Ok(match expr {
-      NatLiteral(_) => Type::Const(Nat),
-      StringLiteral(_) => Type::Const(StringT),
-      BinExp(op, lhs, rhs) => {
-
-        return Err(format!("NOTDONE"))
-      },
-      Call { f, arguments } =>  {
-
-        return Err(format!("NOTDONE"))
-      },
-      Value(name) => {
-        let s = match self.0.get(name) {
-          Some(sigma) => sigma.clone(),
-          None => return Err(format!("Unknown variable: {}", name))
-        };
-        self.instantiate(s)
-      },
-      _ => Type::Const(Unit)
-    })
-  }
-}
-
-
-/* GIANT TODO - use the rust im crate, unless I make this code way less haskell-ish after it's done
-  */
-
-/*
-
-
-pub type TypeResult<T> = Result<T, String>;
-*/
-
-/* TODO this should just check the name against a map, and that map should be pre-populated with
- * types */
-/*
-impl parsing::TypeName {
-  fn to_type(&self) -> TypeResult<Type> {
-	use self::parsing::TypeSingletonName;
-	use self::parsing::TypeName::*;
-	use self::Type::*; use self::TConstOld::*;
-    Ok(match self {
-      Tuple(_) => return Err(format!("Tuples not yet implemented")),
-      Singleton(name) => match name {
-        TypeSingletonName { name, .. } => match &name[..] {
-          /*
-          "Nat" => Const(Nat),
-          "Int" => Const(Int),
-          "Float" => Const(Float),
-          "Bool" => Const(Bool),
-          "String" => Const(StringT),
-          */
-          n => Const(Custom(n.to_string()))
-        }
-      }
-    })
-  }
-}
-*/
-
-
-
-/*
-impl TypeContext {
-  pub fn type_check_ast(&mut self, ast: &parsing::AST) -> TypeResult<String> {
-    let ref block = ast.0;
-    let mut infer = Infer::default();
-    let env = TypeEnvironment::default();
-    let output = infer.infer_block(block, &env);
-    match output {
-      Ok(s) => Ok(format!("{:?}", s)),
-      Err(s) => Err(format!("Error: {:?}", s))
-    }
-  }
-}
-
-// this is the equivalent of the Haskell Infer monad
-#[derive(Debug, Default)]
-struct Infer {
-  _idents: u32,
-}
-
-#[derive(Debug)]
-enum InferError {
-  CannotUnify(MonoType, MonoType),
-  OccursCheckFailed(Rc<String>, MonoType),
-  UnknownIdentifier(Rc<String>),
-  Custom(String),
-}
-
-type InferResult<T> = Result<T, InferError>;
-
-
-impl Infer {
-  fn fresh(&mut self) -> MonoType {
-    let i = self._idents;
-    self._idents += 1;
-    let name = Rc::new(format!("{}", ('a' as u8 + 1) as char));
-    MonoType::Var(name)
-  }
-
-  fn unify(&mut self, a: MonoType, b: MonoType) -> InferResult<Substitution> {
-    use self::InferError::*; use self::MonoType::*;
-    Ok(match (a, b) {
-      (Const(ref a), Const(ref b)) if a == b => Substitution::new(),
-      (Var(ref name), ref var) => Substitution::bind_variable(name, var),
-      (ref var, Var(ref name)) => Substitution::bind_variable(name, var),
-      (Function(box a1, box b1), Function(box a2, box b2)) => {
-        let s1 = self.unify(a1, a2)?;
-        let s2 = self.unify(b1.apply_substitution(&s1), b2.apply_substitution(&s1))?;
-        s1.merge(s2)
-      },
-      (a, b) => return Err(CannotUnify(a, b))
-    })
-  }
-
-  fn infer_block(&mut self, block: &Vec<parsing::Statement>, env: &TypeEnvironment) -> InferResult<MonoType> {
-    use self::parsing::Statement;
-    let mut ret = MonoType::Const(TypeConst::Unit);
-    for statement in block.iter() {
-      ret = match statement {
-        Statement::ExpressionStatement(expr) => {
-          let (sub, ty) = self.infer_expr(expr, env)?;
-          //TODO handle substitution monadically
-
-          ty
-        }
-        Statement::Declaration(decl) => MonoType::Const(TypeConst::Unit),
-      }
-    }
-    Ok(ret)
-  }
-
-  fn infer_expr(&mut self, expr: &parsing::Expression, env: &TypeEnvironment) -> InferResult<(Substitution, MonoType)> {
-    use self::parsing::Expression;
-    match expr {
-      Expression(e, Some(anno)) => self.infer_annotated_expr(e, anno, env),
-      /*
-        let anno_ty = anno.to_type()?;
-        let ty = self.infer_exprtype(&e)?;
-        self.unify(ty, anno_ty)
-      },
-      */
-      Expression(e, None) => self.infer_exprtype(e, env)
-    }
-  }
-
-  fn infer_annotated_expr(&mut self, expr: &parsing::ExpressionType, anno: &parsing::TypeName, env: &TypeEnvironment) -> InferResult<(Substitution, MonoType)> {
-    Err(InferError::Custom(format!("exprtype not done: {:?}", expr)))
-  }
-  fn infer_exprtype(&mut self, expr: &parsing::ExpressionType, env: &TypeEnvironment) -> InferResult<(Substitution, MonoType)> {
-    use self::parsing::ExpressionType::*;
-    use self::TypeConst::*;
-    Ok(match expr {
-      NatLiteral(_) => (Substitution::new(), MonoType::Const(Nat)),
-      FloatLiteral(_) => (Substitution::new(), MonoType::Const(Float)),
-      StringLiteral(_) => (Substitution::new(), MonoType::Const(StringT)),
-      BoolLiteral(_) => (Substitution::new(), MonoType::Const(Bool)),
-      Value(name) => match env.lookup(name) {
-        Some(sigma) => {
-          let tau = self.instantiate(&sigma);
-          (Substitution::new(), tau)
-        },
-        None => return Err(InferError::UnknownIdentifier(name.clone())),
-      },
-      e => return Err(InferError::Custom(format!("Type inference for {:?} not done", e)))
-    })
-  }
-  fn instantiate(&mut self, sigma: &PolyType) -> MonoType {
-    let ref ty: MonoType = sigma.1;
-    let mut subst = Substitution::new();
-
-    for name in sigma.0.iter() {
-      let fresh_mvar = self.fresh();
-      let new = Substitution::bind_variable(name, &fresh_mvar);
-      subst = subst.merge(new);
-    }
-    ty.apply_substitution(&subst)
-  }
-}
-*/
-
-
-
-
-
-
-
-
-
-
-
-
-/* OLD STUFF DOWN HERE */
-
-
-
-/*
-impl TypeContext {
-  fn infer_block(&mut self, statements: &Vec<parsing::Statement>) -> TypeResult<Type> {
-    let mut ret_type = Type::Const(TConst::Unit);
-    for statement in statements {
-      ret_type = self.infer_statement(statement)?;
-    }
-    Ok(ret_type)
-  }
-
-  fn infer_statement(&mut self, statement: &parsing::Statement) -> TypeResult<Type> {
-    use self::parsing::Statement::*;
-    match statement {
-      ExpressionStatement(expr) => self.infer(expr),
-      Declaration(decl) => self.add_declaration(decl),
-    }
-  }
-  fn add_declaration(&mut self, decl: &parsing::Declaration) -> TypeResult<Type> {
-    use self::parsing::Declaration::*;
-    use self::Type::*;
-    match decl {
-      Binding { name, expr, .. } => {
-        let ty = self.infer(expr)?;
-        self.bindings.insert(name.clone(), ty);
-      },
-      _ => return Err(format!("other formats not done"))
-    }
-    Ok(Void)
-  }
-  fn infer(&mut self, expr: &parsing::Expression) -> TypeResult<Type> {
-    use self::parsing::Expression;
-    match expr {
-      Expression(e, Some(anno)) => {
-        let anno_ty = anno.to_type()?;
-        let ty = self.infer_exprtype(&e)?;
-        self.unify(ty, anno_ty)
-      },
-      Expression(e, None) => self.infer_exprtype(e)
-    }
-  }
-  fn infer_exprtype(&mut self, expr: &parsing::ExpressionType) -> TypeResult<Type> {
-    use self::parsing::ExpressionType::*;
-    use self::Type::*; use self::TConst::*;
-    match expr {
-      NatLiteral(_) => Ok(Const(Nat)),
-      FloatLiteral(_) => Ok(Const(Float)),
-      StringLiteral(_) => Ok(Const(StringT)),
-      BoolLiteral(_) => Ok(Const(Bool)),
-      BinExp(op, lhs, rhs) => { /* remember there are both the haskell convention talk and the write you a haskell ways to do this! */
-        match op.get_type()? {
-          Func(box t1, box Func(box t2, box t3)) => {
-            let lhs_ty = self.infer(lhs)?;
-            let rhs_ty = self.infer(rhs)?;
-            self.unify(t1, lhs_ty)?;
-            self.unify(t2, rhs_ty)?;
-            Ok(t3)
-          },
-          other => Err(format!("{:?} is not a binary function type", other))
-        }
-      },
-      PrefixExp(op, expr) => match op.get_type()? {
-        Func(box t1, box t2) => {
-          let expr_ty = self.infer(expr)?;
-          self.unify(t1, expr_ty)?;
-          Ok(t2)
-        },
-        other => Err(format!("{:?} is not a prefix op function type", other))
-      },
-      Value(name) => {
-        match self.bindings.get(name) {
-          Some(ty) => Ok(ty.clone()),
-          None => Err(format!("No binding found for variable: {}", name)),
-        }
-      },
-      Call { f, arguments } => {
-        let mut tf = self.infer(f)?;
-        for arg in arguments.iter() {
-          match tf {
-            Func(box t, box rest) => {
-              let t_arg = self.infer(arg)?;
-              self.unify(t, t_arg)?;
-              tf = rest;
-            },
-            other => return Err(format!("Function call failed to unify; last type: {:?}", other)),
-          }
-        }
-        Ok(tf)
-      },
-      TupleLiteral(expressions) => {
-        let mut types = vec![];
-        for expr in expressions {
-          types.push(self.infer(expr)?);
-        }
-        Ok(Sum(types))
-      },
-      _ => Err(format!("Type not yet implemented"))
-    }
-  }
-  fn unify(&mut self, t1: Type, t2: Type) -> TypeResult<Type> {
-    use self::Type::*;// use self::TConst::*;
-    match (t1, t2) {
-      (Const(ref a), Const(ref b)) if a == b => Ok(Const(a.clone())),
-      (a, b) => Err(format!("Types {:?} and {:?} don't unify", a, b))
-    }
-  }
-}
-*/
-
-
-#[cfg(test)]
-mod tests {
-  /*
-  use super::{Type, TConst, TypeContext};
-  use super::Type::*;
-  use super::TConst::*;
-  use std::rc::Rc;
-  use std::cell::RefCell;
-
-  macro_rules! type_test {
-    ($input:expr, $correct:expr) => {
-      {
-      let symbol_table = Rc::new(RefCell::new(SymbolTable::new()));
-      let mut tc = TypeContext::new(symbol_table);
-      let ast = ::ast::parse(::tokenizing::tokenize($input)).0.unwrap() ;
-      //tc.add_symbols(&ast);
-      assert_eq!($correct, tc.infer_block(&ast.0).unwrap())
-      }
-    }
-  }
-
-  #[test]
-  fn basic_inference() {
-    type_test!("30", Const(Nat));
-    //type_test!("fn x(a: Int): Bool {}; x(1)", TConst(Boolean));
-  }
-  */
-}

schala-repl-codegen/Cargo.toml

@@ -1,11 +1,12 @@
 [package]
-name = "schala-codegen"
+name = "schala-repl-codegen"
 version = "0.1.0"
 authors = ["greg <greg.shuflin@protonmail.com>"]
 
 [dependencies]
-syn = { version = "0.13.1", features = ["full", "extra-traits"] }
-quote = "0.5"
+syn = { version = "0.15.6", features = ["full", "extra-traits"] }
+quote = "0.6.8"
+proc-macro2 = "0.4.19"
 schala-repl = { path = "../schala-repl" }
 
 [lib]

schala-repl-codegen/src/lib.rs

@@ -0,0 +1,199 @@
+#![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 looks like:
+ * fn(&mut ProgrammingLanguageInterface, A, 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(self, input_to_next_stage, 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/src/language.rs

@@ -1,6 +1,7 @@
 use std::collections::HashMap;
 use colored::*;
 use std::fmt::Write;
+use std::time;
 
 pub struct LLVMCodeString(pub String);
 
@@ -8,6 +9,7 @@ pub struct LLVMCodeString(pub String);
 pub struct EvalOptions {
   pub execution_method: ExecutionMethod,
   pub debug_passes: HashMap<String, PassDebugOptionsDescriptor>,
+  pub debug_timing: bool,
 }
 
 #[derive(Debug, Hash, PartialEq)]
@@ -35,12 +37,14 @@ impl Default for ExecutionMethod {
 #[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>,
 }
 
@@ -51,18 +55,36 @@ impl UnfinishedComputation {
   pub fn finish(self, text_output: Result<String, String>) -> FinishedComputation {
     FinishedComputation {
       artifacts: self.artifacts,
-      text_output
+      text_output,
+      durations: self.durations,
     }
   }
   pub fn output(self, output: Result<String, String>) -> FinishedComputation {
     FinishedComputation {
       artifacts: self.artifacts,
-      text_output: output
+      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() {
@@ -72,6 +94,11 @@ impl FinishedComputation {
       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(),
@@ -128,7 +155,7 @@ impl TraceArtifact {
 
 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")) }
+    FinishedComputation { artifacts: vec![], text_output: Err(format!("Execution pipeline not done")), durations: vec![] }
   }
 
   fn get_language_name(&self) -> String;
@@ -142,55 +169,7 @@ pub trait ProgrammingLanguageInterface {
   fn custom_interpreter_directives_help(&self) -> String {
     format!(">> No custom interpreter directives specified <<")
   }
-}
-
-/* a pass_chain function signature looks like: 
- * fn(&mut ProgrammingLanguageInterface, A, Option<&mut DebugHandler>) -> Result<B, String>
- *
- * TODO use some kind of failure-handling library to make this better
- */
-
-#[macro_export]
-macro_rules! pass_chain {
-  ($state:expr, $options:expr; $($pass:path), *) => {
-    |text_input| {
-      let mut comp = UnfinishedComputation::default();
-      pass_chain_helper! { ($state, comp, $options); text_input $(, $pass)* }
-    }
-  };
-}
-
-#[macro_export]
-macro_rules! pass_chain_helper {
-  (($state:expr, $comp:expr, $options:expr); $input:expr, $pass:path $(, $rest:path)*) => {
-    {
-      use schala_repl::PassDebugOptionsDescriptor;
-      let pass_name = stringify!($pass);
-      let output = {
-        let ref debug_map = $options.debug_passes;
-        let debug_handle = match debug_map.get(pass_name) {
-          Some(PassDebugOptionsDescriptor { opts }) => {
-            let ptr = &mut $comp;
-            ptr.cur_debug_options = opts.clone();
-            Some(ptr)
-          }
-          _ => None
-        };
-        $pass($state, $input, debug_handle)
-      };
-      match output {
-        Ok(result) => pass_chain_helper! { ($state, $comp, $options); result $(, $rest)* },
-        Err(err) => {
-          $comp.output(Err(format!("Pass {} failed with {:?}", pass_name, err)))
-        }
-      }
-    }
-  };
-  // Done
-  (($state:expr, $comp:expr, $options:expr); $final_output:expr) => {
-    {
-      let final_output: FinishedComputation = $comp.finish(Ok($final_output));
-      final_output
-    }
-  };
+  fn get_doc(&self, _commands: &Vec<&str>) -> Option<String> {
+    None
+  }
 }

schala-repl/src/lib.rs

@@ -17,14 +17,11 @@ extern crate phf;
 
 use std::path::Path;
 use std::fs::File;
-use std::io::{Read, Write};
+use std::io::Read;
 use std::process::exit;
 use std::default::Default;
-use std::fmt::Write as FmtWrite;
-
-use colored::*;
-use itertools::Itertools;
 
+mod repl;
 mod language;
 mod webapp;
 pub mod llvm_wrap;
@@ -84,7 +81,7 @@ pub fn repl_main(generators: Vec<PLIGenerator>) {
 
   match option_matches.free[..] {
     [] | [_] => {
-      let mut repl = Repl::new(languages, initial_index);
+      let mut repl = repl::Repl::new(languages, initial_index);
       repl.run();
     }
     [_, ref filename, _..] => {
@@ -132,359 +129,6 @@ fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInte
   }
 }
 
-#[derive(Clone)]
-enum CommandTree {
-  Terminal(String, Option<String>),
-  NonTerminal(String, Vec<CommandTree>, Option<String>),
-  Top(Vec<CommandTree>),
-}
-
-impl CommandTree {
-  fn term(s: &str, help: Option<&str>) -> CommandTree {
-    CommandTree::Terminal(s.to_string(), help.map(|x| x.to_string()))
-  }
-  fn get_cmd(&self) -> String {
-    match self {
-      CommandTree::Terminal(s, _) => s.to_string(),
-      CommandTree::NonTerminal(s, _, _) => s.to_string(),
-      CommandTree::Top(_) => "".to_string(),
-    }
-  }
-  fn get_help(&self) -> String {
-    match self {
-      CommandTree::Terminal(_, h) => h.as_ref().map(|h| h.clone()).unwrap_or(format!("")),
-      CommandTree::NonTerminal(_, _, h) => h.as_ref().map(|h| h.clone()).unwrap_or(format!("")),
-      CommandTree::Top(_) => "".to_string(),
-    }
-  }
-  fn get_children(&self) -> Vec<String> {
-    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(),
-    }
-  }
-}
-
-struct TabCompleteHandler {
-  sigil: char,
-  top_level_commands: CommandTree,
-}
-
-use linefeed::complete::{Completion, Completer};
-use linefeed::terminal::Terminal;
-
-impl TabCompleteHandler {
-  fn new(sigil: char, top_level_commands: CommandTree) -> TabCompleteHandler {
-    TabCompleteHandler {
-      top_level_commands,
-      sigil,
-    }
-  }
-}
-
-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);
-
-      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.clone()),
-                    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;
-          }
-        }
-      }
-      Some(completions)
-    } else {
-      None
-    }
-  }
-}
-
-struct Repl {
-  options: EvalOptions,
-  languages: Vec<Box<ProgrammingLanguageInterface>>,
-  current_language_index: usize,
-  interpreter_directive_sigil: char,
-  line_reader: linefeed::interface::Interface<linefeed::terminal::DefaultTerminal>,
-}
-
-impl Repl {
-  fn new(languages: Vec<Box<ProgrammingLanguageInterface>>, initial_index: usize) -> Repl {
-    use linefeed::Interface;
-    let i = if initial_index < languages.len() { initial_index } else { 0 };
-
-    let line_reader = Interface::new("schala-repl").unwrap();
-
-    Repl {
-      options: Repl::get_options(),
-      languages: languages,
-      current_language_index: i,
-      interpreter_directive_sigil: ':',
-      line_reader
-    }
-  }
-
-  fn get_cur_language(&self) -> &ProgrammingLanguageInterface {
-    self.languages[self.current_language_index].as_ref()
-  }
-
-  fn get_options() -> EvalOptions {
-    File::open(".schala_repl")
-      .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(".schala_repl")
-      .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 .schala_repl file {}", err);
-    }
-  }
-
-  fn run(&mut self) {
-    use linefeed::ReadResult;
-
-    println!("Schala MetaInterpreter version {}", VERSION_STRING);
-    println!("Type {}help for help with the REPL", self.interpreter_directive_sigil);
-
-    self.line_reader.load_history(".schala_history").unwrap_or(());
-
-    loop {
-      let language_name = self.languages[self.current_language_index].get_language_name();
-      let directives = self.get_directives();
-      let tab_complete_handler = TabCompleteHandler::new(self.interpreter_directive_sigil, directives);
-      self.line_reader.set_completer(std::sync::Arc::new(tab_complete_handler));
-
-      let prompt_str = format!("{} >> ", language_name);
-      self.line_reader.set_prompt(&prompt_str);
-
-      match self.line_reader.read_line() {
-        Err(e) => {
-          println!("Terminal read error: {}", e);
-        },
-        Ok(ReadResult::Eof) => break,
-        Ok(ReadResult::Signal(_)) => break,
-        Ok(ReadResult::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);
-          }
-        }
-      }
-    }
-    self.line_reader.save_history(".schala_history").unwrap_or(());
-    self.save_options();
-    println!("Exiting...");
-  }
-
-  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 sub_opts: Vec<CommandTree> = pass_descriptor.debug_options.iter()
-            .map(|o| CommandTree::term(o, None)).collect();
-          CommandTree::NonTerminal(
-            name.clone(),
-            sub_opts,
-            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::NonTerminal(format!("debug"), vec![
-        CommandTree::term("passes", None),
-        CommandTree::NonTerminal(format!("show"), passes_directives.clone(), None),
-        CommandTree::NonTerminal(format!("hide"), passes_directives.clone(), None),
-      ], Some(format!("show or hide pass info for a given pass, or display the names of all passes"))),
-      CommandTree::NonTerminal(format!("lang"), vec![
-        CommandTree::term("next", None),
-        CommandTree::term("prev", None),
-        CommandTree::NonTerminal(format!("go"), vec![], None)//TODO
-      ], Some(format!("switch between languages, or go directly to a langauge by name"))),
-    ])
-  }
-
-  fn handle_interpreter_directive(&mut self, input: &str) -> Option<String> {
-    let mut iter = input.chars();
-    iter.next();
-    let commands: Vec<&str> = iter
-      .as_str()
-      .split_whitespace()
-      .collect();
-
-    let cmd: &str = match commands.get(0).clone() {
-      None => return None,
-      Some(s) => s
-    };
-
-    match cmd {
-      "exit" | "quit"  => {
-        self.save_options();
-        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),
-      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(&"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"))
-    }
-  }
-}
-
 /*
 pub fn compilation_sequence(llvm_code: LLVMCodeString, sourcefile: &str) {
     use std::process::Command;

schala-repl/src/repl/command_tree.rs

@@ -0,0 +1,53 @@
+
+#[derive(Clone)]
+pub enum CommandTree {
+  Terminal {
+    name: String,
+    help_msg: Option<String>,
+    function: Option<Box<(fn() -> Option<String>)>>,
+  },
+  NonTerminal {
+    name: String,
+    children: Vec<CommandTree>,
+    help_msg: Option<String>,
+    function: Option<Box<(fn() -> Option<String>)>>,
+  },
+  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(s: &str, help: Option<&str>, children: Vec<CommandTree>) -> CommandTree {
+    CommandTree::NonTerminal {
+      name: s.to_string(),
+      help_msg: help.map(|x| x.to_string()),
+      children,
+      function: None,
+    }
+  }
+
+  pub fn get_cmd(&self) -> &str {
+    match self {
+      CommandTree::Terminal { name, .. } => name.as_str(),
+      CommandTree::NonTerminal {name, ..} => name.as_str(),
+      CommandTree::Top(_) => "",
+    }
+  }
+  pub fn get_help(&self) -> &str {
+    match self {
+      CommandTree::Terminal { help_msg, ..} => help_msg.as_ref().map(|s| s.as_str()).unwrap_or(""),
+      CommandTree::NonTerminal { help_msg, .. } => help_msg.as_ref().map(|s| s.as_str()).unwrap_or(""),
+      CommandTree::Top(_) => ""
+    }
+  }
+  pub fn get_children(&self) -> Vec<&str> {
+    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(),
+    }
+  }
+}

schala-repl/src/repl/mod.rs

@@ -0,0 +1,355 @@
+use std::fmt::Write as FmtWrite;
+use std::io::{Read, Write};
+use std::fs::File;
+use std::sync::Arc;
+
+use colored::*;
+use itertools::Itertools;
+use language::{ProgrammingLanguageInterface, EvalOptions,
+  PassDebugOptionsDescriptor};
+mod command_tree;
+use self::command_tree::CommandTree;
+
+const HISTORY_SAVE_FILE: &'static str = ".schala_history";
+const OPTIONS_SAVE_FILE: &'static str = ".schala_repl";
+
+pub struct Repl {
+  options: EvalOptions,
+  languages: Vec<Box<ProgrammingLanguageInterface>>,
+  current_language_index: usize,
+  interpreter_directive_sigil: char,
+  line_reader: ::linefeed::interface::Interface<::linefeed::terminal::DefaultTerminal>,
+}
+
+impl Repl {
+  pub fn new(languages: Vec<Box<ProgrammingLanguageInterface>>, initial_index: usize) -> Repl {
+    use linefeed::Interface;
+    let i = if initial_index < languages.len() { initial_index } else { 0 };
+
+    let line_reader = Interface::new("schala-repl").unwrap();
+
+    Repl {
+      options: Repl::get_options(),
+      languages: languages,
+      current_language_index: i,
+      interpreter_directive_sigil: ':',
+      line_reader
+    }
+  }
+
+  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);
+    println!("Type {}help for help with the REPL", self.interpreter_directive_sigil);
+
+    self.line_reader.load_history(HISTORY_SAVE_FILE).unwrap_or(());
+
+    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();
+
+      match self.line_reader.read_line() {
+        Err(e) => {
+          println!("Terminal read error: {}", e);
+        },
+        Ok(ReadResult::Eof) => break,
+        Ok(ReadResult::Signal(_)) => break,
+        Ok(ReadResult::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);
+          }
+        }
+      }
+    }
+    self.line_reader.save_history(HISTORY_SAVE_FILE).unwrap_or(());
+    self.save_options();
+    println!("Exiting...");
+  }
+
+  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> {
+    let mut iter = input.chars();
+    iter.next();
+    let commands: Vec<&str> = iter
+      .as_str()
+      .split_whitespace()
+      .collect();
+
+    let initial_cmd: &str = match commands.get(0).clone() {
+      None => return None,
+      Some(s) => s
+    };
+
+    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"))
+    }
+  }
+}
+
+struct TabCompleteHandler {
+  sigil: char,
+  top_level_commands: CommandTree,
+}
+
+use linefeed::complete::{Completion, Completer};
+use linefeed::terminal::Terminal;
+
+impl TabCompleteHandler {
+  fn new(sigil: char, top_level_commands: CommandTree) -> TabCompleteHandler {
+    TabCompleteHandler {
+      top_level_commands,
+      sigil,
+    }
+  }
+}
+
+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);
+
+      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(' ')
+                })
+              }
+            }
+            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;
+          }
+        }
+      }
+      Some(completions)
+    } else {
+      None
+    }
+  }
+}

source_files/schala/does_scope_work.schala

@@ -1,12 +1,11 @@
-
-const c = 10
+let c = 10
 
 fn add(a, b) {
-  const c = a + b
+  let c = a + b
   c
 }
 
-var b = 20
+let mut b = 20
 
 println(add(1,2))
 println(c + b)

source_files/schala/first_program.schala

@@ -1,10 +1,15 @@
 fn main() {
-  const a = 10
-  const b = 20
+  let a = 10
+  let b = 20
   a + b
 }
 
-//foo
+//this is a one-line comment
+
+/* this is
+a multiline
+comment
+*/
 
 print(main())
 

source_files/schala/test.schala

@@ -6,7 +6,7 @@ fn sua(x): Int {
 }
 
 
-//const a = getline()
+//let a = getline()
 
 /*
 if a == "true" {