Add a few more things to an Expression-only visitor

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

README.md

@@ -59,6 +59,11 @@ much like Haskell
 Here's a partial list of resources I've made use of in the process
 of learning how to write a programming language.
 
+### General
+
+http://thume.ca/2019/04/18/writing-a-compiler-in-rust/
+http://thume.ca/2019/07/14/a-tour-of-metaprogramming-models-for-generics/
+
 ### Type-checking
 https://skillsmatter.com/skillscasts/10868-inside-the-rust-compiler
 https://www.youtube.com/watch?v=il3gD7XMdmA

TODO.md

@@ -7,8 +7,6 @@
 - cf. the notation mentioned in the cardelli paper, the debug information for the `typechecking` pass should 
 print the generated type variable for every subexpression in an expression
 
-- change 'trait' to 'interface'
-
 - think about idris-related ideas of multiple implementations of a type for an interface (+ vs * impl for monoids, for preorder/inorder/postorder for Foldable)
 
 -should have an Idris-like `cast To From` function
@@ -17,8 +15,6 @@ print the generated type variable for every subexpression in an expression
 
 -idea: the `type` declaration should have some kind of GADT-like syntax
 
--idea: I should make the BNF grammar part of the documentation...
-
 - Idea: if you have a pattern-match where one variant has a variable and the other lacks it
 instead of treating this as a type error, promote the bound variable to an option type
 
@@ -69,6 +65,8 @@ ex.
 
 ## Playing around with conditional syntax ideas
 
+- 
+
 - if/match playground
 
 simple if
@@ -107,17 +105,3 @@ if the only two guard patterns are true and false, then the abbreviated syntax:
 `'if' discriminator 'then' block_or_expr 'else' block_or_expr`
 can replace `'if' discriminator '{' 'true' 'then' block_or_expr; 'false' 'then' block_or_expr '}'`
 
-
-
-
-
-
-
-
-
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-
-
-

VISITOR_NOTES

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

schala-lang/language/src/ast.rs

@@ -43,7 +43,13 @@ pub enum Statement {
 
 pub type Block = Vec<Meta<Statement>>;
 pub type ParamName = Rc<String>;
-pub type FormalParam = (ParamName, Option<TypeIdentifier>);
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct FormalParam {
+  pub name: ParamName,
+  pub default: Option<Expression>,
+  pub anno: Option<TypeIdentifier>
+}
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum Declaration {
@@ -94,8 +100,20 @@ pub enum Variant {
 }
 
 #[derive(Debug, PartialEq, Clone)]
-pub struct Expression(pub ExpressionKind, pub Option<TypeIdentifier>);
+pub struct Expression {
+  pub kind: ExpressionKind,
+  pub type_anno: Option<TypeIdentifier>
+}
 
+impl Expression {
+  pub fn new(kind: ExpressionKind) -> Expression {
+    Expression { kind, type_anno: None }
+  }
+
+  pub fn with_anno(kind: ExpressionKind, type_anno: TypeIdentifier) -> Expression {
+    Expression { kind, type_anno: Some(type_anno) }
+  }
+}
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum TypeIdentifier {
@@ -125,7 +143,7 @@ pub enum ExpressionKind {
   },
   Call {
     f: Box<Meta<Expression>>,
-    arguments: Vec<Meta<Expression>>,
+    arguments: Vec<Meta<InvocationArgument>>,
   },
   Index {
     indexee: Box<Meta<Expression>>,
@@ -151,6 +169,16 @@ pub enum ExpressionKind {
   ListLiteral(Vec<Meta<Expression>>),
 }
 
+#[derive(Debug, PartialEq, Clone)]
+pub enum InvocationArgument {
+  Positional(Expression),
+  Keyword {
+    name: Rc<String>,
+    expr: Expression,
+  },
+  Ignored
+}
+
 #[derive(Debug, PartialEq, Clone)]
 pub enum Discriminator {
   Simple(Expression),

schala-lang/language/src/builtin.rs

@@ -25,6 +25,7 @@ impl BinOp {
       Slash => "/",
       LAngleBracket => "<",
       RAngleBracket => ">",
+      Equals => "=",
       _ => return None
     };
     Some(BinOp::from_sigil(s))
@@ -47,6 +48,7 @@ impl BinOp {
       Slash => "/",
       LAngleBracket => "<",
       RAngleBracket => ">",
+      Equals => "=",
       _ => return None
     };
     let default = 10_000_000;

schala-lang/language/src/eval.rs

@@ -532,8 +532,10 @@ mod eval_tests {
   fn test_basic_eval() {
     test_in_fresh_env!("1 + 2", "3");
     test_in_fresh_env!("let mut a = 1; a = 2", "Unit");
+    /*
     test_in_fresh_env!("let mut a = 1; a = 2; a", "2");
     test_in_fresh_env!(r#"("a", 1 + 2)"#, r#"("a", 3)"#);
+    */
   }
 
   #[test]

schala-lang/language/src/lib.rs

@@ -4,7 +4,7 @@
 #![feature(slice_patterns, box_patterns, box_syntax)]
 
 //! `schala-lang` is where the Schala programming language is actually implemented. 
-//! It defines the `Schala` type, which contains the state for a Schala REPL, and implements
+//! The crate defines the `Schala` type, which contains the state for a Schala REPL, and implements
 //! `ProgrammingLanguageInterface` and the chain of compiler passes for it.
 
 extern crate itertools;
@@ -17,28 +17,10 @@ extern crate schala_repl;
 extern crate schala_lang_codegen;
 extern crate ena;
 
-use stopwatch::Stopwatch;
-
-use std::time::Duration;
-use std::cell::RefCell;
-use std::rc::Rc;
-use std::collections::HashSet;
-
-use itertools::Itertools;
-use schala_repl::{ProgrammingLanguageInterface,
-ComputationRequest, ComputationResponse,
-LangMetaRequest, LangMetaResponse, GlobalOutputStats,
-DebugResponse, DebugAsk};
-
-macro_rules! bx {
-  ($e:expr) => { Box::new($e) }
-}
-
 #[macro_use]
 mod util;
 #[macro_use]
 mod typechecking;
-
 mod tokenizing;
 mod ast;
 mod parsing;
@@ -46,287 +28,7 @@ mod symbol_table;
 mod builtin;
 mod reduced_ast;
 mod eval;
+mod schala;
+mod visitor;
 
-/// All bits of state necessary to parse and execute a Schala program are stored in this struct.
-/// `state` represents the execution state for the AST-walking interpreter, the other fields
-/// should be self-explanatory.
-pub struct Schala {
-  source_reference: SourceReference,
-  state: eval::State<'static>,
-  symbol_table: Rc<RefCell<symbol_table::SymbolTable>>,
-  type_context: typechecking::TypeContext<'static>,
-  active_parser: Option<parsing::Parser>,
-}
-
-impl Schala {
-  fn handle_docs(&self, source: String) -> LangMetaResponse {
-    LangMetaResponse::Docs {
-      doc_string: format!("Schala item `{}` : <<Schala-lang documentation not yet implemented>>", source)
-    }
-  }
-}
-
-impl Schala {
-  /// Creates a new Schala environment *without* any prelude.
-  fn new_blank_env() -> Schala {
-    let symbols = Rc::new(RefCell::new(symbol_table::SymbolTable::new()));
-    Schala {
-      source_reference: SourceReference::new(),
-      symbol_table: symbols.clone(),
-      state: eval::State::new(symbols),
-      type_context: typechecking::TypeContext::new(),
-      active_parser: None,
-    }
-  }
-
-  /// Creates a new Schala environment with the standard prelude, which is defined as ordinary
-  /// Schala code in the file `prelude.schala`
-  pub fn new() -> Schala {
-    let prelude = include_str!("prelude.schala");
-    let mut s = Schala::new_blank_env();
-
-    let request = ComputationRequest { source: prelude, debug_requests: HashSet::default() };
-    s.run_computation(request);
-    s
-  }
-
-  fn handle_debug_immediate(&self, request: DebugAsk) -> DebugResponse {
-    use DebugAsk::*;
-    match request {
-      Timing => DebugResponse { ask: Timing, value: format!("Invalid") },
-      ByStage { stage_name } => match &stage_name[..] {
-        "symbol-table" => {
-          let value = self.symbol_table.borrow().debug_symbol_table();
-          DebugResponse {
-            ask: ByStage { stage_name: format!("symbol-table") },
-            value
-          }
-        },
-        s => {
-          DebugResponse {
-            ask: ByStage { stage_name: s.to_string() },
-            value: format!("Not-implemented")
-          }
-        }
-      }
-    }
-  }
-}
-
-fn tokenizing(input: &str, _handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<Vec<tokenizing::Token>, String> {
-  let tokens = tokenizing::tokenize(input);
-  comp.map(|comp| {
-    let token_string = tokens.iter().map(|t| t.to_string_with_metadata()).join(", ");
-    comp.add_artifact(token_string);
-  });
-
-  let errors: Vec<String> = tokens.iter().filter_map(|t| t.get_error()).collect();
-  if errors.len() == 0 {
-    Ok(tokens)
-  } else {
-    Err(format!("{:?}", errors))
-  }
-}
-
-fn parsing(input: Vec<tokenizing::Token>, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
-  use crate::parsing::Parser;
-
-  let mut parser = match handle.active_parser.take() {
-    None => Parser::new(input),
-    Some(parser) => parser
-  };
-
-  let ast = parser.parse();
-  let _trace = parser.format_parse_trace();
-
-  comp.map(|_comp| {
-    /*
-    //TODO need to control which of these debug stages get added
-    let opt = comp.cur_debug_options.get(0).map(|s| s.clone());
-    match opt {
-      None => comp.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast))),
-      Some(ref s) if s == "compact" => comp.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast))),
-      Some(ref s) if s == "expanded" => comp.add_artifact(TraceArtifact::new("ast", format!("{:#?}", ast))),
-      Some(ref s) if s == "trace" => comp.add_artifact(TraceArtifact::new_parse_trace(trace)),
-      Some(ref x) => println!("Bad parsing debug option: {}", x),
-    };
-    */
-  });
-  ast.map_err(|err| format_parse_error(err, handle))
-}
-
-fn format_parse_error(error: parsing::ParseError, handle: &mut Schala) -> String {
-  let line_num = error.token.line_num;
-  let ch = error.token.char_num;
-  let line_from_program = handle.source_reference.get_line(line_num);
-  let location_pointer = format!("{}^", " ".repeat(ch));
-
-  let line_num_digits = format!("{}", line_num).chars().count();
-  let space_padding = " ".repeat(line_num_digits);
-
-  format!(r#"
-{error_msg}
-{space_padding} |
-{line_num} | {}
-{space_padding} | {}
-"#, line_from_program, location_pointer, error_msg=error.msg, space_padding=space_padding, line_num=line_num)
-}
-
-fn symbol_table(input: ast::AST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
-  let add = handle.symbol_table.borrow_mut().add_top_level_symbols(&input);
-  match add {
-    Ok(()) => {
-      let debug = handle.symbol_table.borrow().debug_symbol_table();
-      comp.map(|comp| comp.add_artifact(debug));
-      Ok(input)
-    },
-    Err(msg) => Err(msg)
-  }
-}
-
-fn typechecking(input: ast::AST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
-  let result = handle.type_context.typecheck(&input);
-
-  comp.map(|comp| {
-    comp.add_artifact(match result {
-      Ok(ty) => ty.to_string(),
-      Err(err) => format!("Type error: {}", err.msg)
-    });
-  });
-
-  Ok(input)
-}
-
-fn ast_reducing(input: ast::AST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<reduced_ast::ReducedAST, String> {
-  let ref symbol_table = handle.symbol_table.borrow();
-  let output = input.reduce(symbol_table);
-  comp.map(|comp| comp.add_artifact(format!("{:?}", output)));
-  Ok(output)
-}
-
-fn eval(input: reduced_ast::ReducedAST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<String, String> {
-  comp.map(|comp| comp.add_artifact(handle.state.debug_print()));
-  let evaluation_outputs = handle.state.evaluate(input, true);
-  let text_output: Result<Vec<String>, String> = evaluation_outputs
-    .into_iter()
-    .collect();
-
-  let eval_output: Result<String, String> = text_output
-    .map(|v| { v.into_iter().intersperse(format!("\n")).collect() });
-  eval_output
-}
-
-/// Represents lines of source code
-struct SourceReference {
-  lines: Option<Vec<String>>
-}
-
-impl SourceReference {
-  fn new() -> SourceReference {
-    SourceReference { lines: None }
-  }
-
-  fn load_new_source(&mut self, source: &str) {
-    //TODO this is a lot of heap allocations - maybe there's a way to make it more efficient?
-    self.lines = Some(source.lines().map(|s| s.to_string()).collect()); }
-
-  fn get_line(&self, line: usize) -> String {
-    self.lines.as_ref().and_then(|x| x.get(line).map(|s| s.to_string())).unwrap_or(format!("NO LINE FOUND"))
-  }
-}
-
-#[derive(Default)]
-struct PassDebugArtifact {
-  artifacts: Vec<String>
-}
-impl PassDebugArtifact {
-  fn add_artifact(&mut self, artifact: String) {
-    self.artifacts.push(artifact)
-  }
-}
-
-fn stage_names() -> Vec<&'static str> {
-  vec![
-    "tokenizing",
-    "parsing",
-    "symbol-table",
-    "typechecking",
-    "ast-reduction",
-    "ast-walking-evaluation"
-  ]
-}
-
-
-impl ProgrammingLanguageInterface for Schala {
-  fn get_language_name(&self) -> String { format!("Schala") }
-  fn get_source_file_suffix(&self) -> String { format!("schala") }
-
-  fn run_computation(&mut self, request: ComputationRequest) -> ComputationResponse {
-    struct PassToken<'a> {
-      schala: &'a mut Schala,
-      stage_durations: &'a mut Vec<(String, Duration)>,
-      sw: &'a Stopwatch,
-      debug_requests: &'a HashSet<DebugAsk>,
-      debug_responses: &'a mut Vec<DebugResponse>,
-    }
-
-    fn output_wrapper<Input, Output, F>(n: usize, func: F, input: Input, tok: &mut PassToken) -> Result<Output, String>
-      where F: Fn(Input, &mut Schala, Option<&mut PassDebugArtifact>) -> Result<Output, String>
-    {
-      let stage_names = stage_names();
-      let mut debug_artifact = if tok.debug_requests.contains(&DebugAsk::ByStage { stage_name: stage_names[n].to_string() }) {
-        Some(PassDebugArtifact::default())
-      } else {
-        None
-      };
-      let output = func(input, tok.schala, debug_artifact.as_mut());
-      tok.stage_durations.push((stage_names[n].to_string(), tok.sw.elapsed()));
-      if let Some(artifact) = debug_artifact {
-        for value in artifact.artifacts.into_iter() {
-          let resp = DebugResponse {
-            ask: DebugAsk::ByStage { stage_name: stage_names[n].to_string() },
-            value,
-          };
-          tok.debug_responses.push(resp);
-        }
-      }
-      output
-    }
-
-    let ComputationRequest { source, debug_requests } = request;
-    self.source_reference.load_new_source(source);
-    let sw = Stopwatch::start_new();
-    let mut stage_durations = Vec::new();
-    let mut debug_responses = Vec::new();
-    let mut tok = PassToken { schala: self, stage_durations: &mut stage_durations, sw: &sw, debug_requests: &debug_requests, debug_responses: &mut debug_responses };
-
-    let main_output: Result<String, String> = Ok(source)
-      .and_then(|source| output_wrapper(0, tokenizing, source, &mut tok))
-      .and_then(|tokens| output_wrapper(1, parsing, tokens, &mut tok))
-      .and_then(|ast| output_wrapper(2, symbol_table, ast, &mut tok))
-      .and_then(|ast| output_wrapper(3, typechecking, ast, &mut tok))
-      .and_then(|ast| output_wrapper(4, ast_reducing, ast, &mut tok))
-      .and_then(|reduced_ast| output_wrapper(5, eval, reduced_ast, &mut tok));
-
-    let total_duration = sw.elapsed();
-    let global_output_stats = GlobalOutputStats {
-      total_duration, stage_durations
-    };
-
-    ComputationResponse {
-      main_output,
-      global_output_stats,
-      debug_responses,
-    }
-  }
-
-  fn request_meta(&mut self, request: LangMetaRequest) -> LangMetaResponse {
-    match request {
-      LangMetaRequest::StageNames => LangMetaResponse::StageNames(stage_names().iter().map(|s| s.to_string()).collect()),
-      LangMetaRequest::Docs { source } => self.handle_docs(source),
-      LangMetaRequest::ImmediateDebug(debug_request) =>
-        LangMetaResponse::ImmediateDebug(self.handle_debug_immediate(debug_request)),
-      LangMetaRequest::Custom { .. } => LangMetaResponse::Custom { kind: format!("not-implemented"), value: format!("") }
-    }
-  }
-}
+pub use schala::Schala;

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

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

schala-lang/language/src/reduced_ast.rs

@@ -118,10 +118,21 @@ fn reduce_block(block: &Block, symbol_table: &SymbolTable) -> Vec<Stmt> {
   block.iter().map(|stmt| stmt.node().reduce(symbol_table)).collect()
 }
 
+impl InvocationArgument {
+  fn reduce(&self, symbol_table: &SymbolTable) -> Expr {
+    use crate::ast::InvocationArgument::*;
+    match self {
+      Positional(ex) => ex.reduce(symbol_table),
+      Keyword { .. } => Expr::UnimplementedSigilValue,
+      Ignored => Expr::UnimplementedSigilValue,
+    }
+  }
+}
+
 impl Expression {
   fn reduce(&self, symbol_table: &SymbolTable) -> Expr {
     use crate::ast::ExpressionKind::*;
-    let ref input = self.0;
+    let ref input = self.kind;
     match input {
       NatLiteral(n) => Expr::Lit(Lit::Nat(*n)),
       FloatLiteral(f) => Expr::Lit(Lit::Float(*f)),
@@ -138,10 +149,7 @@ impl Expression {
         },
         _ => Expr::Val(name.clone()),
       },
-      Call { f, arguments } => Expr::Call {
-        f: Box::new(f.node().reduce(symbol_table)),
-        args: arguments.iter().map(|arg| arg.node().reduce(symbol_table)).collect(),
-      },
+      Call { f, arguments } =>  reduce_call_expression(f, arguments, symbol_table),
       TupleLiteral(exprs) => Expr::Tuple(exprs.iter().map(|e| e.node().reduce(symbol_table)).collect()),
       IfExpression { discriminator, body } => reduce_if_expression(discriminator, body, symbol_table),
       Lambda { params, body, .. } => reduce_lambda(params, body, symbol_table),
@@ -157,11 +165,18 @@ impl Expression {
 fn reduce_lambda(params: &Vec<FormalParam>, body: &Block, symbol_table: &SymbolTable) -> Expr {
   Expr::Func(Func::UserDefined {
     name: None,
-    params: params.iter().map(|param| param.0.clone()).collect(),
+    params: params.iter().map(|param| param.name.clone()).collect(),
     body: reduce_block(body, symbol_table),
   })
 }
 
+fn reduce_call_expression(func: &Meta<Expression>, arguments: &Vec<Meta<InvocationArgument>>, symbol_table: &SymbolTable) -> Expr {
+  Expr::Call {
+    f: Box::new(func.node().reduce(symbol_table)),
+    args: arguments.iter().map(|arg| arg.node().reduce(symbol_table)).collect(),
+  }
+}
+
 fn reduce_if_expression(discriminator: &Discriminator, body: &IfExpressionBody, symbol_table: &SymbolTable) -> Expr {
   let cond = Box::new(match *discriminator {
     Discriminator::Simple(ref expr) => expr.reduce(symbol_table),
@@ -362,7 +377,7 @@ impl Declaration {
         name: name.clone(),
         func: Func::UserDefined {
           name: Some(name.clone()),
-          params: params.iter().map(|param| param.0.clone()).collect(),
+          params: params.iter().map(|param| param.name.clone()).collect(),
           body: reduce_block(&statements, symbol_table),
         }
       },

schala-lang/language/src/schala.rs

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

schala-lang/language/src/symbol_table.rs

@@ -169,9 +169,9 @@ impl SymbolTable {
 
   fn add_function_signature(&mut self, signature: &Signature, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
     let mut local_type_context = LocalTypeContext::new();
-    let types = signature.params.iter().map(|param| match param {
-      (_, Some(type_identifier)) => Rc::new(format!("{:?}", type_identifier)),
-      (_, None) => local_type_context.new_universal_type()
+    let types = signature.params.iter().map(|param| match param.anno {
+      Some(ref type_identifier) => Rc::new(format!("{:?}", type_identifier)),
+      None => local_type_context.new_universal_type()
     }).collect();
     self.add_new_symbol(&signature.name, scope_name_stack, SymbolSpec::Func(types));
     Ok(())

schala-lang/language/src/tokenizing.rs

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

schala-lang/language/src/typechecking.rs

@@ -289,14 +289,22 @@ impl<'a> TypeContext<'a> {
     Ok(ty!(Unit))
   }
 
+  fn invoc(&mut self, invoc: &InvocationArgument) -> InferResult<Type> {
+    use InvocationArgument::*;
+    match invoc {
+      Positional(expr) => self.expr(expr),
+      _ => Ok(ty!(Nat)) //TODO this is wrong
+    }
+  }
+
   fn expr(&mut self, expr: &Expression) -> InferResult<Type> {
     match expr {
-      Expression(expr_type, Some(anno)) => {
-        let t1 = self.expr_type(expr_type)?;
+      Expression { kind, type_anno: Some(anno) } => {
+        let t1 = self.expr_type(kind)?;
         let t2 = self.get_type_from_name(anno)?;
         self.unify(t2, t1)
       },
-      Expression(expr_type, None) => self.expr_type(expr_type)
+      Expression { kind, type_anno: None } => self.expr_type(kind)
     }
   }
 
@@ -361,7 +369,7 @@ impl<'a> TypeContext<'a> {
 
   fn lambda(&mut self, params: &Vec<FormalParam>, type_anno: &Option<TypeIdentifier>, _body: &Block) -> InferResult<Type> {
     let argument_types: InferResult<Vec<Type>> = params.iter().map(|param: &FormalParam| {
-      if let (_, Some(type_identifier)) = param {
+      if let FormalParam { anno: Some(type_identifier), ..  } = param {
         self.get_type_from_name(type_identifier)
       } else {
         Ok(Type::Var(self.fresh_type_variable()))
@@ -376,9 +384,9 @@ impl<'a> TypeContext<'a> {
     Ok(ty!(argument_types, ret_type))
   }
 
-  fn call(&mut self, f: &Expression, args: &Vec<Meta<Expression>>) -> InferResult<Type> {
+  fn call(&mut self, f: &Expression, args: &Vec<Meta<InvocationArgument>>) -> InferResult<Type> {
     let tf = self.expr(f)?;
-    let arg_types: InferResult<Vec<Type>> = args.iter().map(|ex| self.expr(ex.node())).collect();
+    let arg_types: InferResult<Vec<Type>> = args.iter().map(|ex| self.invoc(ex.node())).collect();
     let arg_types = arg_types?;
     self.handle_apply(tf, arg_types)
   }

schala-lang/language/src/util.rs

@@ -2,6 +2,10 @@ use std::collections::HashMap;
 use std::hash::Hash;
 use std::cmp::Eq;
 
+macro_rules! bx {
+  ($e:expr) => { Box::new($e) }
+}
+
 #[derive(Default, Debug)]
 pub struct ScopeStack<'a, T: 'a, V: 'a>  where T: Hash + Eq {
   parent: Option<&'a ScopeStack<'a, T, V>>,

schala-lang/language/src/visitor.rs

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

schala-repl/Cargo.toml

@@ -11,13 +11,13 @@ itertools = "0.5.8"
 getopts = "0.2.18"
 lazy_static = "0.2.8"
 maplit = "*"
-colored = "1.7"
+colored = "1.8"
 serde = "1.0.91"
 serde_derive = "1.0.91"
 serde_json = "1.0.15"
 phf = "0.7.12"
 includedir = "0.2.0"
-linefeed = "0.5.0"
+linefeed = "0.6.0"
 regex = "0.2"
 
 [build-dependencies]

schala-repl/src/language.rs

@@ -38,7 +38,16 @@ pub struct GlobalOutputStats {
 #[derive(Debug, Clone, Hash, Eq, PartialEq, Deserialize, Serialize)]
 pub enum DebugAsk {
   Timing,
-  ByStage { stage_name: String },
+  ByStage { stage_name: String, token: Option<String> },
+}
+
+impl DebugAsk {
+  pub fn is_for_stage(&self, name: &str) -> bool {
+    match self {
+      DebugAsk::ByStage { stage_name, .. } if stage_name == name => true,
+      _ => false
+    }
+  }
 }
 
 pub struct DebugResponse {

schala-repl/src/lib.rs

@@ -51,7 +51,7 @@ pub fn start_repl(langs: Vec<Box<dyn ProgrammingLanguageInterface>>) {
   };
 }
 
-fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInterface>>) {
+fn run_noninteractive(filename: &str, languages: Vec<Box<dyn ProgrammingLanguageInterface>>) {
   let path = Path::new(filename);
   let ext = path.extension().and_then(|e| e.to_str()).unwrap_or_else(|| {
     println!("Source file lacks extension");

schala-repl/src/repl/command_tree.rs

@@ -1,32 +1,34 @@
-use super::Repl;
-
-pub type BoxedCommandFunction = Box<(fn(&mut Repl, &[&str]) -> Option<String>)>;
+use super::{Repl, InterpreterDirectiveOutput};
+use crate::repl::directive_actions::DirectiveAction;
+use colored::*;
 
 /// A CommandTree is either a `Terminal` or a `NonTerminal`. When command parsing reaches the first
-/// Terminal, it will execute the `BoxedCommandFunction` found there with any remaining arguments
+/// Terminal, it will use the `DirectiveAction` found there to find an appropriate function to execute,
+/// and then execute it with any remaining arguments
 #[derive(Clone)]
 pub enum CommandTree {
   Terminal {
     name: String,
     children: Vec<CommandTree>,
     help_msg: Option<String>,
-    function: BoxedCommandFunction,
+    action: DirectiveAction,
   },
   NonTerminal {
     name: String,
     children: Vec<CommandTree>,
     help_msg: Option<String>,
+    action: DirectiveAction,
   },
   Top(Vec<CommandTree>),
 }
 
 impl CommandTree {
   pub fn nonterm_no_further_tab_completions(s: &str, help: Option<&str>) -> CommandTree {
-    CommandTree::NonTerminal {name: s.to_string(), help_msg: help.map(|x| x.to_string()), children: vec![] }
+    CommandTree::NonTerminal {name: s.to_string(), help_msg: help.map(|x| x.to_string()), children: vec![], action: DirectiveAction::Null }
   }
 
-  pub fn terminal(s: &str, help: Option<&str>, children: Vec<CommandTree>, function: BoxedCommandFunction) -> CommandTree {
-    CommandTree::Terminal {name: s.to_string(), help_msg: help.map(|x| x.to_string()), function, children }
+  pub fn terminal(s: &str, help: Option<&str>, children: Vec<CommandTree>, action: DirectiveAction) -> CommandTree {
+    CommandTree::Terminal {name: s.to_string(), help_msg: help.map(|x| x.to_string()), children, action}
   }
 
   pub fn nonterm(s: &str, help: Option<&str>, children: Vec<CommandTree>) -> CommandTree {
@@ -34,20 +36,10 @@ impl CommandTree {
       name: s.to_string(),
       help_msg: help.map(|x| x.to_string()),
       children,
+      action: DirectiveAction::Null
     }
   }
 
-  /*
-  pub fn nonterm_with_function(s: &str, help: Option<&str>, children: Vec<CommandTree>, func: BoxedCommandFunction) -> CommandTree {
-    CommandTree::NonTerminal {
-      name: s.to_string(),
-      help_msg: help.map(|x| x.to_string()),
-      children,
-      function: Some(func),
-    }
-  }
-  */
-
   pub fn get_cmd(&self) -> &str {
     match self {
       CommandTree::Terminal { name, .. } => name.as_str(),
@@ -62,12 +54,46 @@ impl CommandTree {
       CommandTree::Top(_) => ""
     }
   }
-  pub fn get_children(&self) -> Vec<&str> {
+  pub fn get_children(&self) -> &Vec<CommandTree> {
     use CommandTree::*;
     match self {
       Terminal { children, .. } |
       NonTerminal { children, .. } |
-      Top(children) => children.iter().map(|x| x.get_cmd()).collect()
+      Top(children) => children
+    }
+  }
+  pub fn get_subcommands(&self) -> Vec<&str> {
+    self.get_children().iter().map(|x| x.get_cmd()).collect()
+  }
+
+  pub fn perform(&self, repl: &mut Repl, arguments: &Vec<&str>) -> InterpreterDirectiveOutput {
+    let mut dir_pointer: &CommandTree = self;
+    let mut idx = 0;
+
+    let res: Result<(DirectiveAction, usize), String> = loop {
+      match dir_pointer {
+        CommandTree::Top(subcommands) | CommandTree::NonTerminal { children: subcommands, .. } => {
+          let next_command = match arguments.get(idx) {
+            Some(cmd) => cmd,
+            None => break Err(format!("Command requires arguments"))
+          };
+          idx += 1;
+          match subcommands.iter().find(|sc| sc.get_cmd() == *next_command) {
+            Some(command_tree) => {
+              dir_pointer = command_tree;
+            },
+            None => break Err(format!("Command {} not found", next_command))
+          };
+        },
+        CommandTree::Terminal { action, .. } => {
+          break Ok((action.clone(), idx));
+        },
+      }
+    };
+
+    match res {
+      Ok((action, idx)) => action.perform(repl, &arguments[idx..]),
+      Err(err) => Some(err.red().to_string())
     }
   }
 }

schala-repl/src/repl/directive_actions.rs

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

schala-repl/src/repl/directives.rs

@@ -1,100 +1,44 @@
-use std::fmt::Write as FmtWrite;
-use itertools::Itertools;
-
-use crate::repl::Repl;
 use crate::repl::command_tree::CommandTree;
-use crate::language::{LangMetaRequest, LangMetaResponse, DebugAsk, DebugResponse}; 
+use crate::repl::directive_actions::DirectiveAction;
 
 pub fn directives_from_pass_names(pass_names: &Vec<String>) -> CommandTree {
   let passes_directives: Vec<CommandTree> = pass_names.iter()
-    .map(|pass_name| { CommandTree::nonterm_no_further_tab_completions(pass_name, None) })
+    .map(|pass_name| {
+      if pass_name == "parsing" {
+        CommandTree::nonterm(pass_name, None, vec![
+          CommandTree::nonterm_no_further_tab_completions("compact", None),
+          CommandTree::nonterm_no_further_tab_completions("expanded", None),
+          CommandTree::nonterm_no_further_tab_completions("trace", None),
+        ])
+      } else {
+        CommandTree::nonterm_no_further_tab_completions(pass_name, None) 
+      }
+    })
     .collect();
+  CommandTree::Top(get_list(&passes_directives, true))
+}
 
-  CommandTree::Top(vec![
-    CommandTree::terminal("exit", Some("exit the REPL"), vec![], Box::new(|repl: &mut Repl, _cmds: &[&str]| {
-      repl.save_before_exit();
-      ::std::process::exit(0)
-    })),
-    CommandTree::terminal("quit", Some("exit the REPL"), vec![], Box::new(|repl: &mut Repl, _cmds: &[&str]| {
-      repl.save_before_exit();
-      ::std::process::exit(0)
-    })),
-    CommandTree::terminal("help", Some("Print this help message"), vec![], Box::new(|repl: &mut Repl, cmds: &[&str]| {
-      Some(repl.print_help_message(cmds))
-    })),
+fn get_list(passes_directives: &Vec<CommandTree>, include_help: bool) -> Vec<CommandTree> {
+  use DirectiveAction::*;
+
+  vec![
+    CommandTree::terminal("exit", Some("exit the REPL"), vec![], QuitProgram),
+    CommandTree::terminal("quit", Some("exit the REPL"), vec![], QuitProgram),
+    CommandTree::terminal("help", Some("Print this help message"), if include_help { get_list(passes_directives, false) } else { vec![] }, Help),
     CommandTree::nonterm("debug",
       Some("Configure debug information"),
       vec![
-        CommandTree::terminal("list-passes", Some("List all registered compiler passes"), vec![], Box::new(|repl: &mut Repl, _cmds: &[&str]| {
-          let language_state = repl.get_cur_language_state();
-          let pass_names = match language_state.request_meta(LangMetaRequest::StageNames) {
-            LangMetaResponse::StageNames(names) => names,
-            _ => vec![],
-          };
-
-          let mut buf = String::new();
-          for pass in pass_names.iter().map(|name| Some(name)).intersperse(None) {
-            match pass {
-              Some(pass) => write!(buf, "{}", pass).unwrap(),
-              None => write!(buf, " -> ").unwrap(),
-            }
-          }
-          Some(buf)
-        })),
-        CommandTree::terminal("show-immediate", None, passes_directives.clone(),
-        Box::new(|repl: &mut Repl, cmds: &[&str]| {
-          let cur_state = repl.get_cur_language_state();
-          let stage_name = match cmds.get(1) {
-            Some(s) => s.to_string(),
-            None => return Some(format!("Must specify a thing to debug")),
-          };
-          let meta = LangMetaRequest::ImmediateDebug(DebugAsk::ByStage { stage_name: stage_name.clone() });
-
-          let response = match cur_state.request_meta(meta) {
-            LangMetaResponse::ImmediateDebug(DebugResponse { ask, value }) => {
-              if (ask != DebugAsk::ByStage { stage_name: stage_name }) {
-                return Some(format!("Didn't get debug stage requested"));
-              }
-              value
-            },
-            _ => return Some(format!("Invalid language meta response")),
-          };
-          Some(response)
-        })),
-        CommandTree::terminal("show", None, passes_directives.clone(), Box::new(|repl: &mut Repl, cmds: &[&str]| {
-          let stage_name = match cmds.get(0) {
-            Some(s) => s.to_string(),
-            None => return Some(format!("Must specify a stage to show")),
-          };
-          let ask = DebugAsk::ByStage { stage_name };
-          repl.options.debug_asks.insert(ask);
-          None
-        })),
-        CommandTree::terminal("hide", None, passes_directives.clone(), Box::new(|repl: &mut Repl, cmds: &[&str]| {
-          let stage_name = match cmds.get(0) {
-            Some(s) => s.to_string(),
-            None => return Some(format!("Must specify a stage to hide")),
-          };
-          let ask = DebugAsk::ByStage { stage_name };
-          repl.options.debug_asks.remove(&ask);
-          None
-        })),
+        CommandTree::terminal("list-passes", Some("List all registered compiler passes"), vec![], ListPasses),
+        CommandTree::terminal("show-immediate", None, passes_directives.clone(), ShowImmediate),
+        CommandTree::terminal("show", Some("Show debug output for a specific pass"), passes_directives.clone(), Show),
+        CommandTree::terminal("hide", Some("Hide debug output for a specific pass"), passes_directives.clone(), Hide),
         CommandTree::nonterm("total-time", None, vec![
-          CommandTree::terminal("on", None, vec![], Box::new(|repl: &mut Repl, _: &[&str]| {
-            repl.options.show_total_time = true;
-            None
-          })),
-          CommandTree::terminal("off", None, vec![], Box::new(turn_off)),
+          CommandTree::terminal("on", None, vec![], TotalTimeOn), 
+          CommandTree::terminal("off", None, vec![], TotalTimeOff),
         ]),
         CommandTree::nonterm("stage-times", Some("Computation time per-stage"), vec![
-          CommandTree::terminal("on", None, vec![], Box::new(|repl: &mut Repl, _: &[&str]| {
-            repl.options.show_stage_times = true;
-            None
-          })),
-          CommandTree::terminal("off", None, vec![], Box::new(|repl: &mut Repl, _: &[&str]|  {
-            repl.options.show_stage_times = false;
-            None
-          })),
+          CommandTree::terminal("on", None, vec![], StageTimeOn),
+          CommandTree::terminal("off", None, vec![], StageTimeOff),
         ])
       ]
     ),
@@ -106,21 +50,6 @@ pub fn directives_from_pass_names(pass_names: &Vec<String>) -> CommandTree {
         CommandTree::nonterm("go", None, vec![]),
       ]
     ),
-    CommandTree::terminal("doc", Some("Get language-specific help for an item"), vec![], Box::new(|repl: &mut Repl, cmds: &[&str]| {
-      cmds.get(0).map(|cmd| {
-        let source = cmd.to_string();
-        let meta = LangMetaRequest::Docs { source };
-        let cur_state = repl.get_cur_language_state();
-        match cur_state.request_meta(meta) {
-          LangMetaResponse::Docs { doc_string } => Some(doc_string),
-          _ => Some(format!("Invalid doc response"))
-        }
-      }).unwrap_or(Some(format!(":docs needs an argument")))
-    }))
-  ])
-}
-
-fn turn_off(repl: &mut Repl, _cmds: &[&str]) -> Option<String> {
-  repl.options.show_total_time = false;
-  None
+    CommandTree::terminal("doc", Some("Get language-specific help for an item"), vec![], Doc),
+  ]
 }

schala-repl/src/repl/help.rs

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

schala-repl/src/repl/mod.rs

@@ -1,47 +1,43 @@
-use std::fmt::Write as FmtWrite;
 use std::sync::Arc;
 use std::collections::HashSet;
 
-use colored::*;
 use crate::language::{ProgrammingLanguageInterface,
-ComputationRequest, ComputationResponse,
-DebugAsk, LangMetaResponse, LangMetaRequest};
+ComputationRequest, LangMetaResponse, LangMetaRequest};
 
 mod command_tree;
-use self::command_tree::{CommandTree, BoxedCommandFunction};
+use self::command_tree::CommandTree;
 mod repl_options;
 use repl_options::ReplOptions;
+mod directive_actions;
 mod directives;
 use directives::directives_from_pass_names;
+mod help;
+mod response;
+use response::ReplResponse;
 
 const HISTORY_SAVE_FILE: &'static str = ".schala_history";
 const OPTIONS_SAVE_FILE: &'static str = ".schala_repl";
 
+type InterpreterDirectiveOutput = Option<String>;
+
 pub struct Repl {
-  interpreter_directive_sigil: char,
+  pub interpreter_directive_sigil: char,
   line_reader: ::linefeed::interface::Interface<::linefeed::terminal::DefaultTerminal>,
-  language_states: Vec<Box<ProgrammingLanguageInterface>>,
+  language_states: Vec<Box<dyn ProgrammingLanguageInterface>>,
   options: ReplOptions,
-  directives: CommandTree,
 }
 
 impl Repl {
-  pub fn new(mut initial_states: Vec<Box<ProgrammingLanguageInterface>>) -> Repl {
+  pub fn new(initial_states: Vec<Box<dyn ProgrammingLanguageInterface>>) -> Repl {
     use linefeed::Interface;
     let line_reader = Interface::new("schala-repl").unwrap();
     let interpreter_directive_sigil = ':';
 
-    let pass_names = match initial_states[0].request_meta(LangMetaRequest::StageNames) {
-      LangMetaResponse::StageNames(names) => names,
-      _ => vec![],
-    };
-
     Repl {
       interpreter_directive_sigil,
       line_reader,
       language_states: initial_states,
       options: ReplOptions::new(),
-      directives: directives_from_pass_names(&pass_names)
     }
   }
 
@@ -77,12 +73,16 @@ impl Repl {
         Ok(Eof) | Ok(Signal(_)) => break,
         Ok(Input(ref input)) => {
           self.line_reader.add_history_unique(input.to_string());
-          let output = match input.chars().nth(0) {
-            Some(ch) if ch == self.interpreter_directive_sigil => self.handle_interpreter_directive(input),
-            _ => Some(self.handle_input(input)),
-          };
-          if let Some(o) = output {
-            println!("=> {}", o);
+          match input.chars().nth(0) {
+            Some(ch) if ch == self.interpreter_directive_sigil => match self.handle_interpreter_directive(input) {
+              Some(directive_output) => println!("<> {}", directive_output),
+              None => (),
+            },
+            _ => {
+              for repl_response in self.handle_input(input) {
+                println!("{}", repl_response);
+              }
+            }
           }
         }
       }
@@ -101,130 +101,37 @@ impl Repl {
     self.options.save_to_file(OPTIONS_SAVE_FILE);
   }
 
-  fn get_function_from_directives<'a>(directives: &'a CommandTree, commands: &Vec<&str>) -> Result<(&'a BoxedCommandFunction, usize), String> {
-    let mut dir_pointer: &CommandTree = &directives;
-    let mut idx = 0;
-
-    loop {
-      match dir_pointer {
-        CommandTree::Top(subcommands) | CommandTree::NonTerminal { children: subcommands, .. } => {
-          let next_command = match commands.get(idx) {
-            Some(cmd) => cmd,
-            None => break Err(format!("Command requires arguments"))
-          };
-          idx += 1;
-          match subcommands.iter().find(|sc| sc.get_cmd() == *next_command) {
-            Some(command_tree) => {
-              dir_pointer = command_tree;
-            },
-            None => break Err(format!("Command {} not found", next_command))
-          };
-        },
-        CommandTree::Terminal { function, .. } => {
-          break Ok((function, idx));
-        },
-      }
-    }
-  }
-
-  fn handle_interpreter_directive(&mut self, input: &str) -> Option<String> {
+  fn handle_interpreter_directive(&mut self, input: &str) -> InterpreterDirectiveOutput {
     let mut iter = input.chars();
     iter.next();
-    let commands: Vec<&str> = iter
+    let arguments: Vec<&str> = iter
       .as_str()
       .split_whitespace()
       .collect();
 
-    if commands.len() < 1 {
+    if arguments.len() < 1 {
       return None;
     }
 
     let directives = self.get_directives();
-    let result: Result<(&BoxedCommandFunction, _), String> = Repl::get_function_from_directives(&directives, &commands);
-    match result {
-      Ok((f, idx)) => f(self, &commands[idx..]),
-      Err(err) => Some(err.red().to_string())
-    }
+    directives.perform(self, &arguments)
   }
 
-  fn print_help_message(&mut self, commands_passed_to_help: &[&str] ) -> String {
-    let mut buf = String::new();
-    let directives = match self.get_directives() {
-      CommandTree::Top(children) => children,
-      _ => panic!("Top-level CommandTree not Top")
-    };
-
-    match commands_passed_to_help {
-      [] => {
-        writeln!(buf, "MetaInterpreter options").unwrap();
-        writeln!(buf, "-----------------------").unwrap();
-
-        for directive in directives {
-          let trailer = " ";
-          writeln!(buf, "{}{}- {}", directive.get_cmd(), trailer, directive.get_help()).unwrap();
-        }
-
-        let ref lang = self.get_cur_language_state();
-        writeln!(buf, "").unwrap();
-        writeln!(buf, "Language-specific help for {}", lang.get_language_name()).unwrap();
-        writeln!(buf, "-----------------------").unwrap();
-      },
-      _ => {
-        writeln!(buf, "Command-specific help not available yet").unwrap();
-      }
-    };
-    buf
-  }
-
-  fn get_cur_language_state(&mut self) -> &mut Box<ProgrammingLanguageInterface> {
+  fn get_cur_language_state(&mut self) -> &mut Box<dyn ProgrammingLanguageInterface> {
     //TODO this is obviously not complete
     &mut self.language_states[0]
   }
 
-  fn handle_input(&mut self, input: &str) -> String {
+  fn handle_input(&mut self, input: &str) -> Vec<ReplResponse> {
     let mut debug_requests = HashSet::new();
     for ask in self.options.debug_asks.iter() {
       debug_requests.insert(ask.clone());
     }
 
-    let request = ComputationRequest {
-      source: input,
-      debug_requests,
-    };
-
+    let request = ComputationRequest { source: input, debug_requests };
     let ref mut language_state = self.get_cur_language_state();
     let response = language_state.run_computation(request);
-
-    self.handle_computation_response(response)
-  }
-
-  fn handle_computation_response(&mut self, response: ComputationResponse) -> String {
-    let mut buf = String::new();
-
-    if self.options.show_total_time {
-      buf.push_str(&format!("Total duration: {:?}\n", response.global_output_stats.total_duration));
-    }
-
-    if self.options.show_stage_times {
-      buf.push_str(&format!("{:?}\n", response.global_output_stats.stage_durations));
-    }
-
-
-    for debug_resp in response.debug_responses {
-      let stage_name = match debug_resp.ask {
-        DebugAsk::ByStage { stage_name } => stage_name,
-        _ => continue,
-      };
-      let s = format!("{} - {}\n", stage_name, debug_resp.value);
-      buf.push_str(&s);
-    }
-
-    buf.push_str(&match response.main_output {
-      Ok(s) => s,
-      Err(e) => format!("{} {}", "Error".red(), e)
-    });
-
-    buf
+    response::handle_computation_response(response, &self.options)
   }
 
   fn get_directives(&mut self) -> CommandTree {
@@ -276,7 +183,7 @@ impl<T: Terminal> Completer<T> for TabCompleteHandler {
             _ => 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() {
+          for cmd in command_tree.map(|x| x.get_subcommands()).unwrap_or(vec![]).into_iter() {
             if cmd.starts_with(word) {
               completions.push(Completion {
                 completion: format!("{}{}", if top { ":" } else { "" }, cmd),

schala-repl/src/repl/response.rs

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

src/main.rs

@@ -9,7 +9,7 @@ use schala_repl::{ProgrammingLanguageInterface, start_repl};
 extern { }
 
 fn main() {
-  let langs: Vec<Box<ProgrammingLanguageInterface>> = vec![Box::new(schala_lang::Schala::new())];
+  let langs: Vec<Box<dyn ProgrammingLanguageInterface>> = vec![Box::new(schala_lang::Schala::new())];
   start_repl(langs);
 }