Remove old reduced_ast, eval

This involved fixing how the ScopeResolver handles local bindings. I
probably want to rewrite much of that code.

Cargo.lock

@@ -60,7 +60,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "690a62be8920ccf773ee00ef0968649b0e724cda8bd5b12286302b4ae955fdf5"
 dependencies = [
  "backtrace-sys",
- "cfg-if",
+ "cfg-if 0.1.10",
  "libc",
  "rustc-demangle",
 ]
@@ -119,6 +119,12 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "cgmath"
 version = "0.16.1"
@@ -161,7 +167,7 @@ version = "0.6.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "04973fa96e96579258a5091af6003abde64af786b860f18622b82e026cca60e6"
 dependencies = [
- "cfg-if",
+ "cfg-if 0.1.10",
  "lazy_static 1.4.0",
 ]
 
@@ -355,7 +361,7 @@ version = "0.4.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "14b6052be84e6b71ab17edffc2eeabf5c2c3ae1fdb464aae35ac50c67a44e1f7"
 dependencies = [
- "cfg-if",
+ "cfg-if 0.1.10",
 ]
 
 [[package]]
@@ -410,7 +416,7 @@ checksum = "6c722bee1037d430d0f8e687bbdbf222f27cc6e4e68d5caf630857bb2b6dbdce"
 dependencies = [
  "bitflags",
  "cc",
- "cfg-if",
+ "cfg-if 0.1.10",
  "libc",
  "void",
 ]
@@ -428,7 +434,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2ad2a91a8e869eeb30b9cb3119ae87773a8f4ae617f41b1eb9c154b2905f7bd6"
 dependencies = [
  "memchr",
- "version_check",
+ "version_check 0.1.5",
 ]
 
 [[package]]
@@ -567,9 +573,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.4"
+version = "1.0.30"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "afdc77cc74ec70ed262262942ebb7dac3d479e9e5cfa2da1841c0806f6cdabcc"
+checksum = "edc3358ebc67bc8b7fa0c007f945b0b18226f78437d61bec735a9eb96b61ee70"
 dependencies = [
  "unicode-xid 0.2.0",
 ]
@@ -585,11 +591,11 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "1.0.2"
+version = "1.0.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "053a8c8bcc71fcce321828dc897a98ab9760bef03a4fc36693c231e5b3216cfe"
+checksum = "38bc8cc6a5f2e3655e0899c1b848643b2562f853f114bfec7be120678e3ace05"
 dependencies = [
- "proc-macro2 1.0.4",
+ "proc-macro2 1.0.30",
 ]
 
 [[package]]
@@ -848,6 +854,7 @@ dependencies = [
  "schala-repl",
  "stopwatch",
  "take_mut",
+ "test-case",
 ]
 
 [[package]]
@@ -905,9 +912,9 @@ version = "1.0.101"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4b133a43a1ecd55d4086bd5b4dc6c1751c68b1bfbeba7a5040442022c7e7c02e"
 dependencies = [
- "proc-macro2 1.0.4",
+ "proc-macro2 1.0.30",
- "quote 1.0.2",
+ "quote 1.0.10",
- "syn 1.0.5",
+ "syn 1.0.80",
 ]
 
 [[package]]
@@ -964,12 +971,12 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "1.0.5"
+version = "1.0.80"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "66850e97125af79138385e9b88339cbcd037e3f28ceab8c5ad98e64f0f1f80bf"
+checksum = "d010a1623fbd906d51d650a9916aaefc05ffa0e4053ff7fe601167f3e715d194"
 dependencies = [
- "proc-macro2 1.0.4",
+ "proc-macro2 1.0.30",
- "quote 1.0.2",
+ "quote 1.0.10",
  "unicode-xid 0.2.0",
 ]
 
@@ -1003,6 +1010,19 @@ dependencies = [
  "phf_codegen",
 ]
 
+[[package]]
+name = "test-case"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3b114ece25254e97bf48dd4bfc2a12bad0647adacfe4cae1247a9ca6ad302cec"
+dependencies = [
+ "cfg-if 1.0.0",
+ "proc-macro2 1.0.30",
+ "quote 1.0.10",
+ "syn 1.0.80",
+ "version_check 0.9.3",
+]
+
 [[package]]
 name = "thread_local"
 version = "0.3.6"
@@ -1057,6 +1077,12 @@ version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "914b1a6776c4c929a602fafd8bc742e06365d4bcbe48c30f9cca5824f70dc9dd"
 
+[[package]]
+name = "version_check"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5fecdca9a5291cc2b8dcf7dc02453fee791a280f3743cb0905f8822ae463b3fe"
+
 [[package]]
 name = "void"
 version = "1.0.2"

TODO.md

@@ -1,11 +1,21 @@
 # Immediate TODOs / General Code Cleanup
 
+## Testing
+
+* Get a test library for running many unit tests working
+* Write a human-readable display of the AST
+* Make an automatic (macro-based?) system for numbering compiler errors, this should be every type of error
+
 ## Symbols
 
+* Add some good printf-debugging impls for SymbolTable-related items
+
 * the symbol table should probably *only* be for global definitions (maybe rename it to reflect this?)
 * dealing with variable lookup w/in functions/closures should probably happen in AST -> ReducedAST
     * b/c that's where we go from a string name to a canonical ID (for e.g. 2nd param in 3rd enclosing scope)
 
+* In fact to prove this works, the symbol table shoudl _parallelize_ the process of checking subscopes for local items
+
 * Old notes on a plan of attack:
 
 1. modify visitor so it can handle scopes

schala-lang/language/Cargo.toml

@@ -17,3 +17,6 @@ assert_matches = "1.5"
 
 schala-lang-codegen = { path = "../codegen" }
 schala-repl = { path = "../../schala-repl" }
+
+[dev-dependencies]
+test-case = "1.2.0"

schala-lang/language/src/ast/mod.rs

@@ -1,13 +1,15 @@
 #![allow(clippy::upper_case_acronyms)]
 #![allow(clippy::enum_variant_names)]
 
+use std::rc::Rc;
+use std::fmt;
+
 mod visitor;
 mod operators;
 
 pub use operators::{PrefixOp, BinOp};
-pub use visitor::{walk_ast, walk_block, ASTVisitor};
+pub use visitor::*;
 
-use std::rc::Rc;
 use crate::derivative::Derivative;
 use crate::tokenizing::Location;
 
@@ -15,7 +17,7 @@ use crate::tokenizing::Location;
 /// the u32 index limits the size of an AST to 2^32 nodes.
 #[derive(Debug, PartialEq, Eq, Hash, Clone, Default)]
 pub struct ItemId {
-  idx: u32,
+  pub idx: u32,
 }
 
 impl ItemId {
@@ -24,6 +26,12 @@ impl ItemId {
   }
 }
 
+impl fmt::Display for ItemId {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "ItemId:{}", self.idx)
+  }
+}
+
 pub struct ItemIdStore {
   last_idx: u32
 }

schala-lang/language/src/ast/operators.rs

@@ -80,8 +80,8 @@ fn binop_precedences(s: &str) -> i32 {
     "<" =>  20,
     "<=" => 20,
     "==" => 40,
-    "=" =>  10,
     "<=>" => 30,
+    "=" =>  5, // Assignment shoudl have highest precedence
     _ => default,
   }
 }

schala-lang/language/src/ast/visitor.rs

@@ -1,18 +1,19 @@
 use crate::ast::*;
 
+#[derive(Debug)]
+pub enum Recursion {
+    Continue,
+    Stop
+}
+
 pub trait ASTVisitor: Sized {
-    fn expression(&mut self, _expression: &Expression) {}
+    fn expression(&mut self, _expression: &Expression) -> Recursion { Recursion::Continue }
-    fn expression_post(&mut self, _expression: &Expression) {}
+    fn declaration(&mut self, _declaration: &Declaration, _id: &ItemId) -> Recursion { Recursion::Continue }
 
-    fn declaration(&mut self, _declaration: &Declaration) {}
+    fn import(&mut self, _import: &ImportSpecifier) -> Recursion { Recursion::Continue }
-    fn declaration_post(&mut self, _declaration: &Declaration) {}
+    fn module(&mut self, _module: &ModuleSpecifier) -> Recursion { Recursion::Continue }
 
-    fn import(&mut self, _import: &ImportSpecifier) {}
+    fn pattern(&mut self, _pat: &Pattern) -> Recursion { Recursion::Continue }
-    fn module(&mut self, _module: &ModuleSpecifier) {}
-    fn module_post(&mut self, _module: &ModuleSpecifier) {}
-
-    fn pattern(&mut self, _pat: &Pattern) {}
-    fn pattern_post(&mut self, _pat: &Pattern) {}
 }
 
 pub fn walk_ast<V: ASTVisitor>(v: &mut V, ast: &AST) {
@@ -27,121 +28,121 @@ pub fn walk_block<V: ASTVisitor>(v: &mut V, block: &Block) {
                 walk_expression(v, expr);
             }
             Declaration(ref decl) => {
-                walk_declaration(v, decl);
+                walk_declaration(v, decl, &statement.id);
             }
-            Import(ref import_spec) => v.import(import_spec),
+            Import(ref import_spec) => {
+                v.import(import_spec);
+            },
             Module(ref module_spec) => {
-                v.module(module_spec);
+                if let Recursion::Continue = v.module(module_spec) {
-                walk_block(v, &module_spec.contents);
+                    walk_block(v, &module_spec.contents);
-                v.module_post(module_spec);
+                }
             }
         }
     }
 }
 
-fn walk_declaration<V: ASTVisitor>(v: &mut V, decl: &Declaration) {
+pub fn walk_declaration<V: ASTVisitor>(v: &mut V, decl: &Declaration, id: &ItemId) {
     use Declaration::*;
 
-    v.declaration(decl);
+    if let Recursion::Continue = v.declaration(decl, id) {
-
+        match decl {
-    match decl {
+            FuncDecl(_sig, block) => {
-        FuncDecl(_sig, block) => {
+                walk_block(v, block);
-            walk_block(v, block);
-        }
-        Binding {
-            name: _,
-            constant: _,
-            type_anno: _,
-            expr,
-        } => {
-            walk_expression(v, expr);
-        }
-        _ => (),
-    };
-    v.declaration_post(decl);
-}
-
-fn walk_expression<V: ASTVisitor>(v: &mut V, expr: &Expression) {
-    use ExpressionKind::*;
-
-    v.expression(expr);
-
-    match &expr.kind {
-        NatLiteral(_) | FloatLiteral(_) | StringLiteral(_) | BoolLiteral(_) | Value(_) => (),
-        BinExp(_, lhs, rhs) => {
-            walk_expression(v, &lhs);
-            walk_expression(v, &rhs);
-        }
-        PrefixExp(_, arg) => {
-            walk_expression(v, &arg);
-        }
-        TupleLiteral(exprs) => {
-            for expr in exprs {
-                walk_expression(v, &expr);
             }
-        }
+            Binding {
-        NamedStruct { name: _, fields } => {
+                name: _,
-            for (_, expr) in fields.iter() {
+                constant: _,
+                type_anno: _,
+                expr,
+            } => {
                 walk_expression(v, expr);
             }
-        }
+            _ => (),
-        Call { f, arguments } => {
+        };
-            walk_expression(v, &f);
+    }
-            for arg in arguments.iter() {
-                match arg {
-                    InvocationArgument::Positional(expr) => walk_expression(v, expr),
-                    InvocationArgument::Keyword { expr, .. } => walk_expression(v, expr), //TODO maybe I can combine this pattern
-                    _ => (),
-                }
-            }
-        }
-        Index { indexee, indexers } => {
-            walk_expression(v, &indexee);
-            for indexer in indexers.iter() {
-                walk_expression(v, indexer);
-            }
-        }
-        IfExpression {
-            discriminator,
-            body,
-        } => {
-            if let Some(d) = discriminator.as_ref() {
-                walk_expression(v, &d);
-            }
-            walk_if_expr_body(v, &body.as_ref());
-        }
-        WhileExpression { condition, body } => {
-            if let Some(d) = condition.as_ref() {
-                walk_expression(v, d);
-            }
-            walk_block(v, &body);
-        }
-        ForExpression { enumerators, body } => {
-            for enumerator in enumerators {
-                walk_expression(v, &enumerator.generator);
-            }
-            match body.as_ref() {
-                ForBody::MonadicReturn(expr) => walk_expression(v, expr),
-                ForBody::StatementBlock(block) => walk_block(v, block),
-            };
-        }
-        Lambda {
-            params: _,
-            type_anno: _,
-            body,
-        } => {
-            walk_block(v, &body);
-        }
-        ListLiteral(exprs) => {
-            for expr in exprs {
-                walk_expression(v, &expr);
-            }
-        }
-    };
-    v.expression_post(expr);
 }
 
-fn walk_if_expr_body<V: ASTVisitor>(v: &mut V, body: &IfExpressionBody) {
+pub fn walk_expression<V: ASTVisitor>(v: &mut V, expr: &Expression) {
+    use ExpressionKind::*;
+
+    if let Recursion::Continue = v.expression(expr) {
+        match &expr.kind {
+            NatLiteral(_) | FloatLiteral(_) | StringLiteral(_) | BoolLiteral(_) | Value(_) => (),
+            BinExp(_, lhs, rhs) => {
+                walk_expression(v, &lhs);
+                walk_expression(v, &rhs);
+            }
+            PrefixExp(_, arg) => {
+                walk_expression(v, &arg);
+            }
+            TupleLiteral(exprs) => {
+                for expr in exprs {
+                    walk_expression(v, &expr);
+                }
+            }
+            NamedStruct { name: _, fields } => {
+                for (_, expr) in fields.iter() {
+                    walk_expression(v, expr);
+                }
+            }
+            Call { f, arguments } => {
+                walk_expression(v, &f);
+                for arg in arguments.iter() {
+                    match arg {
+                        InvocationArgument::Positional(expr) => walk_expression(v, expr),
+                        InvocationArgument::Keyword { expr, .. } => walk_expression(v, expr), //TODO maybe I can combine this pattern
+                        _ => (),
+                    }
+                }
+            }
+            Index { indexee, indexers } => {
+                walk_expression(v, &indexee);
+                for indexer in indexers.iter() {
+                    walk_expression(v, indexer);
+                }
+            }
+            IfExpression {
+                discriminator,
+                body,
+            } => {
+                if let Some(d) = discriminator.as_ref() {
+                    walk_expression(v, &d);
+                }
+                walk_if_expr_body(v, &body.as_ref());
+            }
+            WhileExpression { condition, body } => {
+                if let Some(d) = condition.as_ref() {
+                    walk_expression(v, d);
+                }
+                walk_block(v, &body);
+            }
+            ForExpression { enumerators, body } => {
+                for enumerator in enumerators {
+                    walk_expression(v, &enumerator.generator);
+                }
+                match body.as_ref() {
+                    ForBody::MonadicReturn(expr) => walk_expression(v, expr),
+                    ForBody::StatementBlock(block) => walk_block(v, block),
+                };
+            }
+            Lambda {
+                params: _,
+                type_anno: _,
+                body,
+            } => {
+                walk_block(v, &body);
+            }
+            ListLiteral(exprs) => {
+                for expr in exprs {
+                    walk_expression(v, &expr);
+                }
+            }
+        };
+    }
+}
+
+pub fn walk_if_expr_body<V: ASTVisitor>(v: &mut V, body: &IfExpressionBody) {
     use IfExpressionBody::*;
 
     match body {
@@ -177,36 +178,38 @@ fn walk_if_expr_body<V: ASTVisitor>(v: &mut V, body: &IfExpressionBody) {
                     Condition::Expression(ref expr) => {
                         walk_expression(v, expr);
                     }
-                    _ => (),
+                    Condition::Else => (),
                 }
+                if let Some(ref guard) = arm.guard {
+                    walk_expression(v, &guard);
+                }
+                walk_block(v, &arm.body);
             }
         }
     }
 }
 
-fn walk_pattern<V: ASTVisitor>(v: &mut V, pat: &Pattern) {
+pub fn walk_pattern<V: ASTVisitor>(v: &mut V, pat: &Pattern) {
     use Pattern::*;
 
-    v.pattern(pat);
+    if let Recursion::Continue = v.pattern(pat) {
-
+        match pat {
-    match pat {
+            TuplePattern(patterns) => {
-        TuplePattern(patterns) => {
+                for pat in patterns {
-            for pat in patterns {
+                    walk_pattern(v, pat);
-                walk_pattern(v, pat);
+                }
             }
-        }
+            TupleStruct(_, patterns) => {
-        TupleStruct(_, patterns) => {
+                for pat in patterns {
-            for pat in patterns {
+                    walk_pattern(v, pat);
-                walk_pattern(v, pat);
+                }
             }
-        }
+            Record(_, name_and_patterns) => {
-        Record(_, name_and_patterns) => {
+                for (_, pat) in name_and_patterns {
-            for (_, pat) in name_and_patterns {
+                    walk_pattern(v, pat);
-                walk_pattern(v, pat);
+                }
             }
-        }
+            _ => (),
-        _ => (),
+        };
-    };
+    }
-
-    v.pattern_post(pat);
 }

schala-lang/language/src/eval/mod.rs

@@ -1,444 +0,0 @@
-use std::rc::Rc;
-use std::fmt::Write;
-use std::io;
-
-use crate::util::ScopeStack;
-use crate::reduced_ast::{BoundVars, ReducedAST, Stmt, Expr, Lit, Func, Alternative, Subpattern};
-use crate::builtin::Builtin;
-
-mod test;
-
-pub struct State<'a> {
-  values: ScopeStack<'a, Rc<String>, ValueEntry>,
-}
-
-impl<'a> State<'a> {
-  pub fn new() -> State<'a> {
-    let values = ScopeStack::new(Some("global".to_string()));
-    State { values }
-  }
-
-  #[allow(clippy::ptr_arg)]
-  fn new_frame(&'a self, items: &'a [Node], bound_vars: &BoundVars) -> State<'a> {
-    let mut inner_state = State {
-      values: self.values.new_scope(None),
-    };
-    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(Some).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.is_empty() => format!("{}", name),
-      Node::PrimObject { name, items, .. } => format!("{}{}", name, paren_wrapped_vec(items.iter().map(|x| x.to_repl()))),
-      Node::PrimTuple { items } => paren_wrapped_vec(items.iter().map(|x| x.to_repl())),
-    }
-  }
-  fn is_true(&self) -> bool {
-      matches!(self, Node::Expr(Expr::Lit(crate::reduced_ast::Lit::Bool(true))))
-  }
-}
-
-#[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 {
-    #[allow(clippy::wrong_self_convention)]
-    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(builtin) => format!("<built-in function '{:?}'>", builtin),
-        UserDefined { name: None, .. } => "<function>".to_string(),
-        UserDefined { name: Some(name), .. } => format!("<function '{}'>", name),
-      },
-      Expr::Constructor { type_name, arity, .. } => {
-        format!("<constructor for `{}` arity {}>", type_name, arity)
-      },
-      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(),
-      Lit(_) | Func(_) | Sym(_) | Constructor { .. } |
-       CaseMatch { .. } | UnimplementedSigilValue | ReductionError(_) => 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, 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_else(|| 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),
-        Sym(name) => Ok(match self.values.lookup(&name) {
-          Some(ValueEntry::Binding { val, .. }) => val.clone(),
-          None => return Err(format!("Could not look up symbol {}", name))
-        }),
-        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),
-        CaseMatch { box cond, alternatives } => self.case_match_expression(cond, alternatives),
-        ConditionalTargetSigilValue => Ok(Node::Expr(ConditionalTargetSigilValue)),
-        UnimplementedSigilValue => Err("Sigil value eval not implemented".to_string()),
-        ReductionError(err) => Err(format!("Reduction error: {}", err)),
-      }
-    }
-  }
-
-  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 {} arg(s)", 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,
-      items: evaled_args,
-      tag
-    })
-  }
-
-  fn apply_function(&mut self, f: Func, args: Vec<Expr>) -> EvalResult<Node> {
-    match f {
-      Func::BuiltIn(builtin) => Ok(self.apply_builtin(builtin, 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))),
-        };
-        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, builtin: Builtin, args: Vec<Expr>) -> EvalResult<Node> {
-    use self::Expr::*;
-    use self::Lit::*;
-    use Builtin::*;
-
-    let evaled_args: Result<Vec<Node>, String> = args.into_iter().map(|arg| self.expression(arg.to_node()))
-      .collect();
-    let evaled_args = evaled_args?;
-
-    Ok(match (builtin, evaled_args.as_slice()) {
-      (FieldAccess, &[Node::PrimObject { .. }]) => {
-        //TODO implement field access
-        unimplemented!()
-      },
-      (binop, &[Node::Expr(ref lhs), Node::Expr(ref rhs)]) => match (binop, lhs, rhs) {
-        /* binops */
-        (Add, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l + r)),
-        (Concatenate, Lit(StringLit(ref s1)), Lit(StringLit(ref s2))) => Lit(StringLit(Rc::new(format!("{}{}", s1, s2)))),
-        (Subtract, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l - r)),
-        (Multiply, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l * r)),
-        (Divide, Lit(Nat(l)), Lit(Nat(r))) => Lit(Float((*l as f64)/ (*r as f64))),
-        (Quotient, Lit(Nat(l)), Lit(Nat(r))) => if *r == 0 {
-          return Err("Divide-by-zero error".to_string());
-        } else {
-          Lit(Nat(l / r))
-        },
-        (Modulo, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l % r)),
-        (Exponentiation, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l ^ r)),
-        (BitwiseAnd, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l & r)),
-        (BitwiseOr, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l | r)),
-
-        /* comparisons */
-        (Equality, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l == r)),
-        (Equality, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l == r)),
-        (Equality, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l == r)),
-        (Equality, Lit(Bool(l)), Lit(Bool(r))) => Lit(Bool(l == r)),
-        (Equality, Lit(StringLit(ref l)), Lit(StringLit(ref r))) => Lit(Bool(l == r)),
-
-        (LessThan, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l < r)),
-        (LessThan, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l < r)),
-        (LessThan, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l < r)),
-
-        (LessThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l <= r)),
-        (LessThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l <= r)),
-        (LessThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l <= r)),
-
-        (GreaterThan, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l > r)),
-        (GreaterThan, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l > r)),
-        (GreaterThan, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l > r)),
-
-        (GreaterThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l >= r)),
-        (GreaterThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l >= r)),
-        (GreaterThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l >= r)),
-        _ => return Err("No valid binop".to_string())
-      }.to_node(),
-      (prefix, &[Node::Expr(ref arg)]) => match (prefix, arg) {
-        (BooleanNot, Lit(Bool(true))) => Lit(Bool(false)),
-        (BooleanNot, Lit(Bool(false))) => Lit(Bool(true)),
-        (Negate, Lit(Nat(n))) => Lit(Int(-(*n as i64))),
-        (Negate, Lit(Int(n))) => Lit(Int(-(*n as i64))),
-        (Increment, Lit(Int(n))) => Lit(Int(*n)),
-        (Increment, Lit(Nat(n))) => Lit(Nat(*n)),
-        _ => return Err("No valid prefix op".to_string())
-      }.to_node(),
-
-      /* builtin functions */
-      (IOPrint, &[ref anything]) => {
-        print!("{}", anything.to_repl());
-        Expr::unit().to_node()
-      },
-      (IOPrintLn, &[ref anything]) => {
-        println!("{}", anything.to_repl());
-        Expr::unit().to_node()
-      },
-      (IOGetLine, &[]) => {
-        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()))).to_node()
-      },
-      (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("Conditional with non-boolean condition".to_string())
-    })
-  }
-
-  fn assign_expression(&mut self, val: Expr, expr: Expr) -> EvalResult<Node> {
-    let name = match val  {
-      Expr::Sym(name) => name,
-      _ => return Err("Trying to assign to a non-value".to_string()),
-    };
-
-    let constant = match self.values.lookup(&name) {
-      None => return Err(format!("Constant {} is undefined", name)),
-      Some(ValueEntry::Binding { constant, .. }) => *constant,
-    };
-    if constant {
-      return Err(format!("trying to update {}, a non-mutable binding", name));
-    }
-    let val = self.expression(Node::Expr(expr))?;
-    self.values.insert(name, 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.is_empty() {
-        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.matchable.guard, &cond)? {
-        continue;
-      }
-
-      match cond {
-        Node::PrimObject { ref tag, ref items, .. } => {
-          if alt.matchable.tag.map(|t| t == *tag).unwrap_or(true) {
-            let mut inner_state = self.new_frame(items, &alt.matchable.bound_vars);
-            if all_subpatterns_pass(&mut inner_state, &alt.matchable.subpatterns, items)? {
-              return inner_state.block(alt.item);
-            } else {
-              continue;
-            }
-          }
-        },
-        Node::PrimTuple { ref items } =>  {
-          let mut inner_state = self.new_frame(items, &alt.matchable.bound_vars);
-          if all_subpatterns_pass(&mut inner_state, &alt.matchable.subpatterns, items)? {
-            return inner_state.block(alt.item);
-          } else {
-            continue;
-          }
-        },
-        Node::Expr(ref _e) => {
-          if alt.matchable.tag.is_none() {
-            return self.block(alt.item)
-          }
-        }
-      }
-    }
-    Err(format!("{:?} failed pattern match", cond))
-  }
-}

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

@@ -1,262 +0,0 @@
-#![cfg(test)]
-
-use crate::symbol_table::SymbolTable;
-use crate::reduced_ast::reduce;
-use crate::eval::State;
-
-fn evaluate_all_outputs(input: &str) -> Vec<Result<String, String>> {
-  let ast = crate::util::quick_ast(input);
-
-  let mut symbol_table = SymbolTable::new();
-  symbol_table.process_ast(&ast).unwrap();
-
-  let reduced = reduce(&ast, &symbol_table);
-
-  let mut state = State::new();
-  
-  state.evaluate(reduced, true)
-}
-
-macro_rules! test_in_fresh_env {
-  ($string:expr, $correct:expr) => {
-    {
-      let all_output = evaluate_all_outputs($string);
-      let 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", "()");
-  /*
-     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 op_eval() {
-  test_in_fresh_env!("- 13", "-13");
-  test_in_fresh_env!("10 - 2", "8");
-}
-
-#[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 queque() {
-      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 = Option::Some(9); if x is Option::Some(q) then { q } else { 0 }"#;
-  test_in_fresh_env!(source, "9");
-
-  let source = r#"
-type Option<T> = Some(T) | None
-let x = Option::None; if x is Option::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 = Option::None
-if a { is Option::None then 4, is Option::Some(x) then x }
-"#;
-test_in_fresh_env!(source, "4");
-
-let source = r#"
-type Option<T> = Some(T) | None
-let a = Option::Some(99)
-if a { is Option::None then 4, is Option::Some(x) then x }
-"#;
-test_in_fresh_env!(source, "99");
-
-let source = r#"
-let a = 10
-if a { is 10 then "x", is 4 then "y" }
-"#;
-test_in_fresh_env!(source, "\"x\"");
-
-let source = r#"
-let a = 10
-if a { is 15 then "x", is 10 then "y" }
-"#;
-test_in_fresh_env!(source, "\"y\"");
-}
-
-#[test]
-fn string_pattern() {
-  let source = r#"
-let a = "foo"
-if a { is "foo" then "x", is _ then "y" }
-"#;
-test_in_fresh_env!(source, "\"x\"");
-}
-
-#[test]
-fn boolean_pattern() {
-  let source = r#"
-let a = true
-if a {
-  is true then "x",
-  is false then "y"
-}
-"#;
-test_in_fresh_env!(source, "\"x\"");
-}
-
-#[test]
-fn boolean_pattern_2() {
-  let source = r#"
-let a = false
-if a { is true then "x", is false then "y" }
-"#;
-test_in_fresh_env!(source, "\"y\"");
-}
-
-#[test]
-fn ignore_pattern() {
-  let source = r#"
-type Option<T> = Some(T) | None
-if Option::Some(10) {
-  is _ then "hella"
-}
-"#;
-test_in_fresh_env!(source, "\"hella\"");
-}
-
-#[test]
-fn tuple_pattern() {
-  let source = r#"
-if (1, 2) {
-  is (1, x) then x,
-  is _ then 99
-}
-"#;
-test_in_fresh_env!(source, 2);
-}
-
-
-#[test]
-fn tuple_pattern_2() {
-  let source = r#"
-if (1, 2) {
-  is (10, x) then x,
-  is (y, x) then x + y
-}
-"#;
-test_in_fresh_env!(source, 3);
-}
-
-#[test]
-fn tuple_pattern_3() {
-  let source = r#"
-if (1, 5) {
-  is (10, x) then x,
-  is (1, x) then x
-}
-"#;
-test_in_fresh_env!(source, 5);
-}
-
-#[test]
-fn tuple_pattern_4() {
-  let source = r#"
-if (1, 5) {
-  is (10, x) then x,
-  is (1, x) then 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 = Stuff::Mulch(20)
-let b = Stuff::Jugs(1, "haha")
-let c = Stuff::Mardok
-
-let x = if a {
-  is Stuff::Mulch(20) then "x",
-  is _ then "ERR"
-}
-
-let y = if b {
-  is Stuff::Mulch(n) then "ERR",
-  is Stuff::Jugs(2, _) then "ERR",
-  is Stuff::Jugs(1, s) then s,
-  is _ then "ERR",
-}
-
-let z = if c {
-  is Stuff::Jugs(_, _) then "ERR",
-  is Stuff::Mardok then "NIGH",
-  is _ then "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");
-  }
-
-#[test]
-fn import_all() {
-  let source = r#"
-type Option<T> = Some(T) | None
-import Option::*
-let x = Some(9); if x is Some(q) then { q } else { 0 }"#;
-  test_in_fresh_env!(source, "9");
-}

schala-lang/language/src/lib.rs

@@ -23,8 +23,10 @@ mod tokenizing;
 mod symbol_table;
 mod builtin;
 mod error;
-mod eval;
+//mod eval;
-mod reduced_ast;
+//mod reduced_ast;
+mod reduced_ir;
+mod tree_walk_eval;
 
 mod schala;
 

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

@@ -830,6 +830,55 @@ fn if_expr() {
   }
 }
 
+#[test]
+fn advanced_if_expr() {
+
+    parse_test_wrap_ast! {
+        r#"
+if (45, "panda", false, 2.2) {
+    is (49, "pablo", _, 28.4) then "no"
+    is (_, "panda", _, -2.2) then "yes"
+    is _ then "maybe"
+}"#,
+      exst!(
+        IfExpression {
+          discriminator: Some(bx!(ex!(s r#"(45, "panda", false, 2.2)"#))),
+          body: bx!(IfExpressionBody::CondList(vec![
+            ConditionArm {
+              condition: Condition::Pattern(Pattern::TuplePattern(
+                vec![
+                    Pattern::Literal(PatternLiteral::NumPattern { neg: false, num: NatLiteral(49) }),
+                    Pattern::Literal(PatternLiteral::StringPattern(rc!(pablo))),
+                    Pattern::Ignored,
+                    Pattern::Literal(PatternLiteral::NumPattern { neg: false, num: FloatLiteral(28.4) }),
+                ]
+              )),
+              guard: None,
+              body: vec![exst!(s r#""no""#)],
+            },
+            ConditionArm {
+              condition: Condition::Pattern(Pattern::TuplePattern(
+                vec![
+                    Pattern::Ignored,
+                    Pattern::Literal(PatternLiteral::StringPattern(rc!(panda))),
+                    Pattern::Ignored,
+                    Pattern::Literal(PatternLiteral::NumPattern { neg: true, num: FloatLiteral(2.2) }),
+                ]
+              )),
+              guard: None,
+              body: vec![exst!(s r#""yes""#)],
+            },
+            ConditionArm {
+              condition: Condition::Pattern(Pattern::Ignored),
+              guard: None,
+              body: vec![exst!(s r#""maybe""#)],
+            },
+          ]))
+        }
+      )
+    }
+}
+
 #[test]
 fn modules() {
   parse_test_wrap_ast! {
@@ -890,4 +939,3 @@ fn annotations() {
         }
     };
 }
-

schala-lang/language/src/reduced_ast/mod.rs

@@ -1,514 +0,0 @@
-//! # Reduced AST
-//! The reduced AST is a minimal AST designed to be built from the full AST after all possible
-//! static checks have been done. Consequently, the AST reduction phase does very little error
-//! checking itself - any errors should ideally be caught either by an earlier phase, or are
-//! runtime errors that the evaluator should handle. That said, becuase it does do table lookups
-//! that can in principle fail [especially at the moment with most static analysis not yet complete],
-//! there is an Expr variant `ReductionError` to handle these cases.
-//!
-//! A design decision to make - should the ReducedAST types contain all information about
-//! type/layout necessary for the evaluator to work? If so, then the evaluator should not
-//! have access to the symbol table at all and ReducedAST should carry that information. If not,
-//! then ReducedAST shouldn't be duplicating information that can be queried at runtime from the
-//! symbol table. But I think the former might make sense since ultimately the bytecode will be
-//! built from the ReducedAST.
-
-use std::convert::TryFrom;
-use std::rc::Rc;
-use std::str::FromStr;
-
-use crate::ast::*;
-use crate::builtin::Builtin;
-use crate::symbol_table::{Symbol, SymbolSpec, SymbolTable};
-use crate::util::deref_optional_box;
-
-mod types;
-pub use types::*;
-
-pub fn reduce(ast: &AST, symbol_table: &SymbolTable) -> ReducedAST {
-    let mut reducer = Reducer { symbol_table };
-    reducer.ast(ast)
-}
-
-struct Reducer<'a> {
-    symbol_table: &'a SymbolTable,
-}
-
-impl<'a> Reducer<'a> {
-    fn ast(&mut self, ast: &AST) -> ReducedAST {
-        let mut output = vec![];
-        for statement in ast.statements.iter() {
-            output.push(self.statement(statement));
-        }
-        ReducedAST(output)
-    }
-
-    fn statement(&mut self, stmt: &Statement) -> Stmt {
-        match &stmt.kind {
-            StatementKind::Expression(expr) => Stmt::Expr(self.expression(expr)),
-            StatementKind::Declaration(decl) => self.declaration(decl),
-            StatementKind::Import(_) => Stmt::Noop,
-            StatementKind::Module(modspec) => {
-                for statement in modspec.contents.iter() {
-                    self.statement(statement);
-                }
-                Stmt::Noop
-            }
-        }
-    }
-
-    #[allow(clippy::ptr_arg)]
-    fn block(&mut self, block: &Block) -> Vec<Stmt> {
-        block.iter().map(|stmt| self.statement(stmt)).collect()
-    }
-
-    fn invocation_argument(&mut self, invoc: &InvocationArgument) -> Expr {
-        use crate::ast::InvocationArgument::*;
-        match invoc {
-            Positional(ex) => self.expression(ex),
-            Keyword { .. } => Expr::UnimplementedSigilValue,
-            Ignored => Expr::UnimplementedSigilValue,
-        }
-    }
-
-    fn expression(&mut self, expr: &Expression) -> Expr {
-        use crate::ast::ExpressionKind::*;
-        let input = &expr.kind;
-        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) => self.binop(binop, lhs, rhs),
-            PrefixExp(op, arg) => self.prefix(op, arg),
-            Value(qualified_name) => self.value(qualified_name),
-            Call { f, arguments } => self.reduce_call_expression(f, arguments),
-            TupleLiteral(exprs) => Expr::Tuple(exprs.iter().map(|e| self.expression(e)).collect()),
-            IfExpression {
-                discriminator,
-                body,
-            } => self.reduce_if_expression(deref_optional_box(discriminator), body),
-            Lambda { params, body, .. } => self.reduce_lambda(params, body),
-            NamedStruct { name, fields } => self.reduce_named_struct(name, fields),
-            Index { .. } => Expr::UnimplementedSigilValue,
-            WhileExpression { .. } => Expr::UnimplementedSigilValue,
-            ForExpression { .. } => Expr::UnimplementedSigilValue,
-            ListLiteral { .. } => Expr::UnimplementedSigilValue,
-        }
-    }
-
-    fn value(&mut self, qualified_name: &QualifiedName) -> Expr {
-        let Symbol {
-            local_name, spec, ..
-        } = match self.symbol_table.lookup_symbol(&qualified_name.id) {
-            Some(s) => s,
-            //TODO this causes several evaluation tests to fail, figure out what's going on here
-            //None => return Expr::ReductionError(format!("Symbol {:?} not found", sym_name)),
-            None => {
-                let name = qualified_name.components.last().unwrap().clone();
-                return Expr::Sym(name);
-            }
-        };
-
-        match spec {
-            SymbolSpec::RecordConstructor { .. } => Expr::ReductionError(
-                "AST reducer doesn't expect a RecordConstructor here".to_string(),
-            ),
-            SymbolSpec::DataConstructor {
-                index,
-                arity,
-                type_name,
-            } => Expr::Constructor {
-                type_name: type_name.clone(),
-                name: local_name.clone(),
-                tag: *index,
-                arity: *arity,
-            },
-            SymbolSpec::Func(_) => Expr::Sym(local_name.clone()),
-            SymbolSpec::Binding => Expr::Sym(local_name.clone()), //TODO not sure if this is right, probably needs to eventually be fqsn
-        }
-    }
-
-    #[allow(clippy::ptr_arg)]
-    fn reduce_lambda(&mut self, params: &[FormalParam], body: &Block) -> Expr {
-        Expr::Func(Func::UserDefined {
-            name: None,
-            params: params.iter().map(|param| param.name.clone()).collect(),
-            body: self.block(body),
-        })
-    }
-
-    fn reduce_named_struct(
-        &mut self,
-        name: &QualifiedName,
-        fields: &[(Rc<String>, Expression)],
-    ) -> Expr {
-        let symbol = match self.symbol_table.lookup_symbol(&name.id) {
-            Some(fqsn) => fqsn,
-            None => return Expr::ReductionError(format!("FQSN lookup for name {:?} failed", name)),
-        };
-
-        let (type_name, index, members_from_table) = match &symbol.spec {
-            SymbolSpec::RecordConstructor {
-                members,
-                type_name,
-                index,
-            } => (type_name.clone(), index, members),
-            _ => return Expr::ReductionError("Not a record constructor".to_string()),
-        };
-
-        let arity = members_from_table.len();
-
-        let mut args: Vec<(Rc<String>, Expr)> = fields
-            .iter()
-            .map(|(name, expr)| (name.clone(), self.expression(expr)))
-            .collect();
-
-        args.as_mut_slice()
-            .sort_unstable_by(|(name1, _), (name2, _)| name1.cmp(name2)); //arbitrary - sorting by alphabetical order
-
-        let args = args.into_iter().map(|(_, expr)| expr).collect();
-
-        //TODO make sure this sorting actually works
-        let f = box Expr::Constructor {
-            type_name,
-            name: symbol.local_name.clone(),
-            tag: *index,
-            arity,
-        };
-        Expr::Call { f, args }
-    }
-
-    fn reduce_call_expression(
-        &mut self,
-        func: &Expression,
-        arguments: &[InvocationArgument],
-    ) -> Expr {
-        Expr::Call {
-            f: Box::new(self.expression(func)),
-            args: arguments
-                .iter()
-                .map(|arg| self.invocation_argument(arg))
-                .collect(),
-        }
-    }
-
-    fn reduce_if_expression(
-        &mut self,
-        discriminator: Option<&Expression>,
-        body: &IfExpressionBody,
-    ) -> Expr {
-        let cond = Box::new(match discriminator {
-            Some(expr) => self.expression(expr),
-            None => return Expr::ReductionError("blank cond if-expr not supported".to_string()),
-        });
-
-        match body {
-            IfExpressionBody::SimpleConditional {
-                then_case,
-                else_case,
-            } => {
-                let then_clause = self.block(then_case);
-                let else_clause = match else_case.as_ref() {
-                    None => vec![],
-                    Some(stmts) => self.block(stmts),
-                };
-                Expr::Conditional {
-                    cond,
-                    then_clause,
-                    else_clause,
-                }
-            }
-            IfExpressionBody::SimplePatternMatch {
-                pattern,
-                then_case,
-                else_case,
-            } => {
-                let then_clause = self.block(then_case);
-                let else_clause = match else_case.as_ref() {
-                    None => vec![],
-                    Some(stmts) => self.block(stmts),
-                };
-
-                let alternatives = vec![
-                    pattern.to_alternative(then_clause, self.symbol_table),
-                    Alternative {
-                        matchable: Subpattern {
-                            tag: None,
-                            subpatterns: vec![],
-                            bound_vars: vec![],
-                            guard: None,
-                        },
-                        item: else_clause,
-                    },
-                ];
-
-                Expr::CaseMatch { cond, alternatives }
-            }
-            IfExpressionBody::CondList(ref condition_arms) => {
-                let mut alternatives = vec![];
-                for arm in condition_arms {
-                    match arm.condition {
-                        Condition::Expression(ref _expr) => return Expr::UnimplementedSigilValue,
-                        Condition::Pattern(ref p) => {
-                            let item = self.block(&arm.body);
-                            let alt = p.to_alternative(item, self.symbol_table);
-                            alternatives.push(alt);
-                        }
-                        Condition::TruncatedOp(_, _) => return Expr::UnimplementedSigilValue,
-                        Condition::Else => return Expr::UnimplementedSigilValue,
-                    }
-                }
-                Expr::CaseMatch { cond, alternatives }
-            }
-        }
-    }
-
-    fn binop(&mut self, binop: &BinOp, lhs: &Expression, rhs: &Expression) -> Expr {
-        let operation = Builtin::from_str(binop.sigil()).ok();
-        match operation {
-            Some(Builtin::Assignment) => Expr::Assign {
-                val: Box::new(self.expression(&*lhs)),
-                expr: Box::new(self.expression(&*rhs)),
-            },
-            Some(op) => {
-                let f = Box::new(Expr::Func(Func::BuiltIn(op)));
-                Expr::Call {
-                    f,
-                    args: vec![self.expression(&*lhs), self.expression(&*rhs)],
-                }
-            }
-            None => {
-                //TODO handle a user-defined operation
-                Expr::UnimplementedSigilValue
-            }
-        }
-    }
-
-    fn prefix(&mut self, prefix: &PrefixOp, arg: &Expression) -> Expr {
-        let builtin: Option<Builtin> = TryFrom::try_from(prefix).ok();
-        match builtin {
-            Some(op) => {
-                let f = Box::new(Expr::Func(Func::BuiltIn(op)));
-                Expr::Call {
-                    f,
-                    args: vec![self.expression(arg)],
-                }
-            }
-            None => {
-                //TODO need this for custom prefix ops
-                Expr::UnimplementedSigilValue
-            }
-        }
-    }
-
-    fn declaration(&mut self, declaration: &Declaration) -> Stmt {
-        use self::Declaration::*;
-        match declaration {
-            Binding {
-                name,
-                constant,
-                expr,
-                ..
-            } => Stmt::Binding {
-                name: name.clone(),
-                constant: *constant,
-                expr: self.expression(expr),
-            },
-            FuncDecl(Signature { name, params, .. }, statements) => Stmt::PreBinding {
-                name: name.clone(),
-                func: Func::UserDefined {
-                    name: Some(name.clone()),
-                    params: params.iter().map(|param| param.name.clone()).collect(),
-                    body: self.block(statements),
-                },
-            },
-            TypeDecl { .. } => Stmt::Noop,
-            TypeAlias { .. } => Stmt::Noop,
-            Interface { .. } => Stmt::Noop,
-            Impl { .. } => Stmt::Expr(Expr::UnimplementedSigilValue),
-            Annotation { .. } => Stmt::Noop,
-            _ => Stmt::Expr(Expr::UnimplementedSigilValue),
-        }
-    }
-}
-
-fn handle_symbol(
-    symbol: Option<&Symbol>,
-    inner_patterns: &[Pattern],
-    symbol_table: &SymbolTable,
-) -> Subpattern {
-    use self::Pattern::*;
-    let tag = symbol.map(|symbol| match symbol.spec {
-        SymbolSpec::DataConstructor { index, .. } => index,
-        _ => {
-            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 {
-            VarOrName(qualified_name) => {
-                let symbol_exists = symbol_table.lookup_symbol(&qualified_name.id).is_some();
-                if symbol_exists {
-                    None
-                } else {
-                    let QualifiedName { components, .. } = qualified_name;
-                    if components.len() == 1 {
-                        Some(components[0].clone())
-                    } else {
-                        panic!("Bad variable name in pattern");
-                    }
-                }
-            }
-            _ => None,
-        })
-        .collect();
-
-    let subpatterns = inner_patterns
-        .iter()
-        .map(|p| match p {
-            Ignored => None,
-            VarOrName(_) => 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 {
-            matchable: Subpattern {
-                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(QualifiedName { components, id }, inner_patterns) => {
-                match symbol_table.lookup_symbol(id) {
-                    Some(symbol) => handle_symbol(Some(symbol), inner_patterns, symbol_table),
-                    None => panic!("Symbol {:?} not found", components),
-                }
-            }
-            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),
-            VarOrName(QualifiedName { components, id }) => {
-                // if symbol is Some, treat this as a symbol pattern. If it's None, treat it
-                // as a variable.
-                match symbol_table.lookup_symbol(id) {
-                    Some(symbol) => handle_symbol(Some(symbol), &[], symbol_table),
-                    None => {
-                        println!("Components: {:?}", components);
-                        let name = if components.len() == 1 {
-                            components[0].clone()
-                        } else {
-                            panic!("check this line of code yo");
-                        };
-                        Subpattern {
-                            tag: None,
-                            subpatterns: vec![],
-                            guard: None,
-                            bound_vars: vec![Some(name)],
-                        }
-                    }
-                }
-            }
-        }
-    }
-}
-
-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, ExpressionKind::NatLiteral(n)) => Lit::Nat(*n),
-                    (false, ExpressionKind::FloatLiteral(f)) => Lit::Float(*f),
-                    (true, ExpressionKind::NatLiteral(n)) => Lit::Int(-(*n as i64)),
-                    (true, ExpressionKind::FloatLiteral(f)) => Lit::Float(-f),
-                    _ => panic!("This should never happen"),
-                });
-                let guard = Some(Expr::Call {
-                    f: Box::new(Expr::Func(Func::BuiltIn(Builtin::Equality))),
-                    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(Builtin::Equality))),
-                    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(Builtin::BooleanNot))),
-                        args: vec![Expr::ConditionalTargetSigilValue],
-                    }
-                });
-                Subpattern {
-                    tag: None,
-                    subpatterns: vec![],
-                    guard,
-                    bound_vars: vec![],
-                }
-            }
-        }
-    }
-}

schala-lang/language/src/reduced_ast/types.rs

@@ -1,98 +0,0 @@
-#![allow(clippy::enum_variant_names)]
-
-use crate::builtin::Builtin;
-use std::rc::Rc;
-
-#[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 {
-    Lit(Lit),
-    Sym(Rc<String>), //a Sym is anything that can be looked up by name at runtime - i.e. a function or variable address
-    Tuple(Vec<Expr>),
-    Func(Func),
-    Constructor {
-        type_name: Rc<String>,
-        name: Rc<String>,
-        tag: usize,
-        arity: usize, // n.b. arity here is always the value from the symbol table - if it doesn't match what it's being called with, that's an eval error, eval will handle it
-    },
-    Call {
-        f: Box<Expr>,
-        args: Vec<Expr>,
-    },
-    Assign {
-        val: Box<Expr>, //TODO this probably can't be a val
-        expr: Box<Expr>,
-    },
-    Conditional {
-        cond: Box<Expr>,
-        then_clause: Vec<Stmt>,
-        else_clause: Vec<Stmt>,
-    },
-    ConditionalTargetSigilValue,
-    CaseMatch {
-        cond: Box<Expr>,
-        alternatives: Vec<Alternative>,
-    },
-    UnimplementedSigilValue,
-    ReductionError(String),
-}
-
-impl Expr {
-    // The unit value is an empty tuple
-    pub fn unit() -> Expr {
-        Expr::Tuple(vec![])
-    }
-}
-
-pub type BoundVars = Vec<Option<Rc<String>>>; //remember that order matters here
-
-#[derive(Debug, Clone)]
-pub struct Alternative {
-    pub matchable: Subpattern,
-    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(Builtin),
-    UserDefined {
-        name: Option<Rc<String>>,
-        params: Vec<Rc<String>>,
-        body: Vec<Stmt>,
-    },
-}

schala-lang/language/src/reduced_ir/mod.rs

@@ -0,0 +1,557 @@
+use crate::ast;
+use crate::symbol_table::{DefId, SymbolSpec, SymbolTable};
+use crate::builtin::Builtin;
+
+use std::str::FromStr;
+use std::collections::HashMap;
+
+mod types;
+mod test;
+
+pub use types::*;
+
+pub fn reduce(ast: &ast::AST, symbol_table: &SymbolTable) -> ReducedIR {
+    let reducer = Reducer::new(symbol_table);
+    reducer.reduce(ast)
+}
+
+struct Reducer<'a> {
+    symbol_table: &'a SymbolTable,
+    functions: HashMap<DefId, FunctionDefinition>,
+}
+
+impl<'a> Reducer<'a> {
+    fn new(symbol_table: &'a SymbolTable) -> Self {
+        Self {
+            symbol_table,
+            functions: HashMap::new(),
+        }
+    }
+
+    fn reduce(mut self, ast: &ast::AST) -> ReducedIR {
+        // First reduce all functions
+        // TODO once this works, maybe rewrite it using the Visitor
+        for statement in ast.statements.iter() {
+            self.top_level_statement(&statement);
+        }
+
+        // Then compute the entrypoint statements (which may reference previously-computed
+        // functions by ID)
+        let mut entrypoint = vec![];
+        for statement in ast.statements.iter() {
+            let ast::Statement { id: item_id, kind, .. } = statement;
+            match &kind {
+                ast::StatementKind::Expression(expr) => {
+                    entrypoint.push(Statement::Expression(self.expression(&expr)));
+                },
+                ast::StatementKind::Declaration(ast::Declaration::Binding { name: _, constant, expr, ..}) => {
+                    let symbol = self.symbol_table.lookup_symbol(item_id).unwrap();
+                    let def_id = symbol.def_id().unwrap();
+                    entrypoint.push(Statement::Binding { id: def_id, constant: *constant, expr: self.expression(&expr) });
+                },
+                _ => ()
+            }
+        }
+
+        ReducedIR {
+            functions: self.functions,
+            entrypoint,
+        }
+    }
+
+    fn top_level_statement(&mut self, statement: &ast::Statement) {
+        let ast::Statement { id: item_id, kind, .. } = statement;
+        match kind {
+            ast::StatementKind::Expression(_expr) => {
+                //TODO expressions can in principle contain definitions, but I won't worry
+                //about it now
+                ()
+            },
+            ast::StatementKind::Declaration(decl) => match decl {
+                ast::Declaration::FuncDecl(_, statements) => {
+                    self.insert_function_definition(item_id, statements);
+                },
+                _ => ()
+            },
+            ast::StatementKind::Import(..) => (),
+            ast::StatementKind::Module(_modspec) => {
+                //TODO handle modules
+                ()
+            }
+        }
+    }
+
+    fn function_internal_statement(&mut self, statement: &ast::Statement) -> Option<Statement> {
+        let ast::Statement { id: item_id, kind, .. } = statement;
+        match kind {
+            ast::StatementKind::Expression(expr) => {
+                Some(Statement::Expression(self.expression(expr)))
+            },
+            ast::StatementKind::Declaration(decl) => match decl {
+                ast::Declaration::FuncDecl(_, statements) => {
+                    self.insert_function_definition(item_id, statements);
+                    None
+                },
+                ast::Declaration::Binding { constant, expr, ..} => {
+                    let symbol = self.symbol_table.lookup_symbol(item_id).unwrap();
+                    let def_id = symbol.def_id().unwrap();
+                    Some(Statement::Binding { id: def_id, constant: *constant, expr: self.expression(&expr) })
+                },
+
+                _ => None
+            },
+            _ => None
+        }
+    }
+
+    fn insert_function_definition(&mut self, item_id: &ast::ItemId, statements: &ast::Block) {
+        let symbol = self.symbol_table.lookup_symbol(item_id).unwrap();
+        let def_id = symbol.def_id().unwrap();
+        let function_def = FunctionDefinition {
+            body: self.function_internal_block(statements)
+        };
+        self.functions.insert(def_id, function_def);
+    }
+
+    fn expression(&mut self, expr: &ast::Expression) -> Expression {
+        use crate::ast::ExpressionKind::*;
+
+        match &expr.kind {
+            NatLiteral(n) => Expression::Literal(Literal::Nat(*n)),
+            FloatLiteral(f) => Expression::Literal(Literal::Float(*f)),
+            StringLiteral(s) => Expression::Literal(Literal::StringLit(s.clone())),
+            BoolLiteral(b) => Expression::Literal(Literal::Bool(*b)),
+            BinExp(binop, lhs, rhs) =>  self.binop(binop, lhs, rhs),
+            PrefixExp(op, arg) => self.prefix(op, arg),
+            Value(qualified_name) => self.value(qualified_name),
+            Call { f, arguments } =>  Expression::Call {
+                f: Box::new(self.expression(f)),
+                args: arguments
+                    .iter()
+                    .map(|arg| self.invocation_argument(arg))
+                    .collect(),
+            },
+            TupleLiteral(exprs) => Expression::Tuple(exprs.iter().map(|e| self.expression(e)).collect()),
+            IfExpression { discriminator, body, } => self.reduce_if_expression(discriminator.as_ref().map(|x| x.as_ref()), body),
+            Lambda { params, body, .. } =>  {
+                Expression::Callable(Callable::Lambda {
+                    arity: params.len() as u8,
+                    body: self.function_internal_block(body),
+                })
+            },
+            NamedStruct { .. } => Expression::ReductionError("NamedStruct not implemented".to_string()), //self.reduce_named_struct(name, fields),
+            Index { .. } => Expression::ReductionError("Index expr not implemented".to_string()),
+            WhileExpression { .. } => Expression::ReductionError("While expr not implemented".to_string()),
+            ForExpression { .. } => Expression::ReductionError("For expr not implemented".to_string()),
+            ListLiteral { .. } => Expression::ReductionError("ListLiteral expr not implemented".to_string()),
+        }
+    }
+
+    fn reduce_if_expression(&mut self, discriminator: Option<&ast::Expression>, body: &ast::IfExpressionBody) -> Expression {
+        use  ast::IfExpressionBody::*;
+
+        let cond = Box::new(match discriminator {
+            Some(expr) => self.expression(expr),
+            None => return Expression::ReductionError("blank cond if-expr not supported".to_string()),
+        });
+        match body {
+            SimpleConditional {
+                then_case,
+                else_case,
+            } => {
+                let then_clause = self.function_internal_block(then_case);
+                let else_clause = match else_case.as_ref() {
+                    None => vec![],
+                    Some(stmts) => self.function_internal_block(stmts),
+                };
+                Expression::Conditional {
+                    cond,
+                    then_clause,
+                    else_clause,
+                }
+            },
+            SimplePatternMatch {
+                pattern,
+                then_case,
+                else_case,
+            } => {
+                let alternatives = vec![
+                    Alternative {
+                        pattern: match pattern.reduce(self.symbol_table) {
+                            Ok(p) => p,
+                            Err(e) => return Expression::ReductionError(format!("Bad pattern: {:?}", e)),
+                        },
+                        item: self.function_internal_block(then_case),
+                    },
+                    Alternative {
+                        pattern: Pattern::Ignored,
+                        item: match else_case.as_ref() {
+                            Some(else_case) => self.function_internal_block(else_case),
+                            None => vec![],
+                        },
+                    },
+                ];
+
+                Expression::CaseMatch { cond, alternatives }
+            },
+            CondList(ref condition_arms) => {
+                let mut alternatives = vec![];
+                for arm in condition_arms {
+                    match arm.condition {
+                        ast::Condition::Expression(ref _expr) => return Expression::ReductionError("case-expression".to_string()),
+                        ast::Condition::Pattern(ref pat) => {
+                            let alt = Alternative {
+                                pattern: match pat.reduce(self.symbol_table) {
+                                    Ok(p) => p,
+                                    Err(e) => return Expression::ReductionError(format!("Bad pattern: {:?}", e)),
+                                },
+                                item: self.function_internal_block(&arm.body),
+                            };
+                            alternatives.push(alt);
+                        },
+                        ast::Condition::TruncatedOp(_, _) =>  return Expression::ReductionError("case-expression-trunc-op".to_string()),
+                        ast::Condition::Else => return Expression::ReductionError("case-expression-else".to_string()),
+                    }
+                }
+                Expression::CaseMatch { cond, alternatives }
+            }
+        }
+    }
+
+    fn invocation_argument(&mut self, invoc: &ast::InvocationArgument) -> Expression {
+        use crate::ast::InvocationArgument::*;
+        match invoc {
+            Positional(ex) => self.expression(ex),
+            Keyword { .. } => Expression::ReductionError("Keyword arguments not supported".to_string()),
+            Ignored  => Expression::ReductionError("Ignored arguments not supported".to_string()),
+        }
+    }
+
+    fn function_internal_block(&mut self, statements: &ast::Block) -> Vec<Statement> {
+        statements.iter().filter_map(|stmt| self.function_internal_statement(stmt)).collect()
+    }
+
+    fn prefix(&mut self, prefix: &ast::PrefixOp, arg: &ast::Expression) -> Expression {
+        let builtin: Option<Builtin> = TryFrom::try_from(prefix).ok();
+        match builtin {
+            Some(op) => {
+                Expression::Call {
+                    f: Box::new(Expression::Callable(Callable::Builtin(op))),
+                    args: vec![self.expression(arg)],
+                }
+            }
+            None => {
+                //TODO need this for custom prefix ops
+                Expression::ReductionError("User-defined prefix ops not supported".to_string())
+            }
+        }
+    }
+
+    fn binop(&mut self, binop: &ast::BinOp, lhs: &ast::Expression, rhs: &ast::Expression) -> Expression {
+        use Expression::ReductionError;
+
+        let operation = Builtin::from_str(binop.sigil()).ok();
+        match operation {
+            Some(Builtin::Assignment) => {
+                let lval = match &lhs.kind {
+                    ast::ExpressionKind::Value(qualified_name) => {
+                        if let Some(symbol) = self.symbol_table.lookup_symbol(&qualified_name.id) {
+                            symbol.def_id().unwrap()
+                        } else {
+                            return ReductionError(format!("Couldn't look up name: {:?}", qualified_name));
+                        }
+                    },
+                    _ => return ReductionError("Trying to assign to a non-name".to_string()),
+                };
+
+                Expression::Assign {
+                    lval,
+                    rval: Box::new(self.expression(rhs)),
+                }
+            },
+            Some(op) => Expression::Call {
+                f: Box::new(Expression::Callable(Callable::Builtin(op))),
+                args: vec![self.expression(lhs), self.expression(rhs)],
+            },
+            //TODO handle a user-defined operation
+            None => ReductionError("User-defined operations not supported".to_string())
+        }
+    }
+
+    fn value(&mut self, qualified_name: &ast::QualifiedName) -> Expression {
+        use SymbolSpec::*;
+
+        let symbol = match self.symbol_table.lookup_symbol(&qualified_name.id) {
+            Some(s) => s,
+            None => return Expression::ReductionError(format!("No symbol found for name: {:?}", qualified_name))
+        };
+
+        let def_id = symbol.def_id();
+
+        match symbol.spec() {
+            Func => Expression::Lookup(Lookup::Function(def_id.unwrap())),
+            GlobalBinding => Expression::Lookup(Lookup::GlobalVar(def_id.unwrap())),
+            LocalVariable => Expression::Lookup(Lookup::LocalVar(def_id.unwrap())),
+            FunctionParam(n) => Expression::Lookup(Lookup::Param(n)),
+            DataConstructor { index, arity, type_id } => Expression::Callable(Callable::DataConstructor {
+                type_id: type_id.clone(),
+                arity: arity as u32, //TODO fix up these modifiers
+                tag: index as u32,
+            }),
+            RecordConstructor { .. } => {
+                Expression::ReductionError(format!("The symbol for value {:?} is unexpectdly a RecordConstructor", qualified_name))
+            },
+        }
+    }
+}
+
+impl ast::Pattern {
+    fn reduce(&self, symbol_table: &SymbolTable) -> Result<Pattern, PatternError> {
+        Ok(match self {
+            ast::Pattern::Ignored => Pattern::Ignored,
+            ast::Pattern::TuplePattern(subpatterns) => {
+                let items: Vec<_> = subpatterns.iter().map(|pat| pat.reduce(symbol_table)).collect();
+                let items: Result<Vec<Pattern>, PatternError> = items.into_iter().collect();
+                let items = items?;
+                Pattern::Tuple {
+                    tag: None,
+                    subpatterns: items,
+                }
+            },
+            ast::Pattern::Literal(lit) => Pattern::Literal(match lit {
+                ast::PatternLiteral::NumPattern { neg, num } =>  match (neg, num) {
+                    (false, ast::ExpressionKind::NatLiteral(n)) => Literal::Nat(*n),
+                    (false, ast::ExpressionKind::FloatLiteral(f)) => Literal::Float(*f),
+                    (true, ast::ExpressionKind::NatLiteral(n)) => Literal::Int(-(*n as i64)),
+                    (true, ast::ExpressionKind::FloatLiteral(f)) => Literal::Float(-f),
+                    (_, e) => return Err(format!("Internal error, unexpected pattern literal: {:?}", e).into())
+                },
+                ast::PatternLiteral::StringPattern(s) => Literal::StringLit(s.clone()),
+                ast::PatternLiteral::BoolPattern(b) => Literal::Bool(*b),
+            }),
+            ast::Pattern::TupleStruct(name, subpatterns) => {
+                let symbol = symbol_table.lookup_symbol(&name.id).unwrap();
+                if let SymbolSpec::DataConstructor { index: tag, type_id, arity } = symbol.spec() {
+                    let items: Vec<_> = subpatterns.iter().map(|pat| pat.reduce(symbol_table)).collect();
+                    let items: Result<Vec<Pattern>, PatternError> = items.into_iter().collect();
+                    let items = items?;
+                    Pattern::Tuple {
+                        tag: Some(tag as u32),
+                        subpatterns: items,
+                    }
+                } else {
+                    return Err("Internal error, trying to match something that's not a DataConstructor".into());
+                }
+            },
+            ast::Pattern::VarOrName(name) => {
+                let symbol = symbol_table.lookup_symbol(&name.id).unwrap();
+                match symbol.spec() {
+                    SymbolSpec::DataConstructor { index: tag, type_id, arity } => {
+                        Pattern::Tuple {
+                            tag: Some(tag as u32),
+                            subpatterns: vec![]
+                        }
+                    },
+                    SymbolSpec::LocalVariable => {
+                        let def_id = symbol.def_id().unwrap().clone();
+                        Pattern::Binding(def_id)
+                    },
+                    spec => return Err(format!("Unexpected VarOrName symbol: {:?}", spec).into())
+                }
+            },
+            ast::Pattern::Record(name, /*Vec<(Rc<String>, Pattern)>*/ _) => {
+                unimplemented!()
+            },
+        })
+    }
+}
+
+/*
+impl ast::Pattern {
+    fn to_subpattern(&self, symbol_table: &SymbolTable) -> Subpattern {
+        use ast::Pattern::*;
+        use Expression::ReductionError;
+
+        match self {
+            Ignored => Subpattern {
+                tag: None,
+                subpatterns: vec![],
+                guard: None,
+            },
+            Literal(lit) => lit.to_subpattern(symbol_table),
+            /*
+            TupleStruct(QualifiedName { components, id }, inner_patterns) => {
+                match symbol_table.lookup_symbol(id) {
+                    Some(symbol) => handle_symbol(Some(symbol), inner_patterns, symbol_table),
+                    None => panic!("Symbol {:?} not found", components),
+                }
+            }
+            */
+            _ => Subpattern {
+                tag: None,
+                subpatterns: vec![],
+                guard: None,
+            }
+        }
+            /*
+            TuplePattern(inner_patterns) => handle_symbol(None, inner_patterns, symbol_table),
+            Record(_name, _pairs) => {
+                unimplemented!()
+            }
+            VarOrName(QualifiedName { components, id }) => {
+                // if symbol is Some, treat this as a symbol pattern. If it's None, treat it
+                // as a variable.
+                match symbol_table.lookup_symbol(id) {
+                    Some(symbol) => handle_symbol(Some(symbol), &[], symbol_table),
+                    None => {
+                        println!("Components: {:?}", components);
+                        let name = if components.len() == 1 {
+                            components[0].clone()
+                        } else {
+                            panic!("check this line of code yo");
+                        };
+                        Subpattern {
+                            tag: None,
+                            subpatterns: vec![],
+                            guard: None,
+                            bound_vars: vec![Some(name)],
+                        }
+                    }
+                }
+            }
+            */
+    }
+}
+*/
+
+/*
+fn handle_symbol(
+    symbol: Option<&Symbol>,
+    inner_patterns: &[Pattern],
+    symbol_table: &SymbolTable,
+) -> Subpattern {
+    use ast::Pattern::*;
+
+    let tag = symbol.map(|symbol| match symbol.spec {
+        SymbolSpec::DataConstructor { index, .. } => index,
+        _ => {
+            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 {
+            VarOrName(qualified_name) => {
+                let symbol_exists = symbol_table.lookup_symbol(&qualified_name.id).is_some();
+                if symbol_exists {
+                    None
+                } else {
+                    let QualifiedName { components, .. } = qualified_name;
+                    if components.len() == 1 {
+                        Some(components[0].clone())
+                    } else {
+                        panic!("Bad variable name in pattern");
+                    }
+                }
+            }
+            _ => None,
+        })
+        .collect();
+
+    let subpatterns = inner_patterns
+        .iter()
+        .map(|p| match p {
+            Ignored => None,
+            VarOrName(_) => 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 ast::PatternLiteral {
+    fn to_subpattern(&self, _symbol_table: &SymbolTable) -> Subpattern {
+        use ast::PatternLiteral::*;
+
+        match self {
+            NumPattern { neg, num } => {
+                let comparison = Expression::Literal(match (neg, num) {
+                    (false, ast::ExpressionKind::NatLiteral(n)) => Literal::Nat(*n),
+                    (false, ast::ExpressionKind::FloatLiteral(f)) => Literal::Float(*f),
+                    (true, ast::ExpressionKind::NatLiteral(n)) => Literal::Int(-(*n as i64)),
+                    (true, ast::ExpressionKind::FloatLiteral(f)) => Literal::Float(-f),
+                    _ => panic!("This should never happen"),
+                });
+                unimplemented!()
+                /*
+                let guard = Some(Expr::Call {
+                    f: Box::new(Expr::Func(Func::BuiltIn(Builtin::Equality))),
+                    args: vec![comparison, Expr::ConditionalTargetSigilValue],
+                });
+                Subpattern {
+                    tag: None,
+                    subpatterns: vec![],
+                    guard,
+                }
+                */
+            }
+            _ => unimplemented!()
+            /*
+            StringPattern(s) => {
+                let guard = Some(Expr::Call {
+                    f: Box::new(Expr::Func(Func::BuiltIn(Builtin::Equality))),
+                    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(Builtin::BooleanNot))),
+                        args: vec![Expr::ConditionalTargetSigilValue],
+                    }
+                });
+                Subpattern {
+                    tag: None,
+                    subpatterns: vec![],
+                    guard,
+                    bound_vars: vec![],
+                }
+            }
+            */
+        }
+    }
+}
+*/

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

@@ -0,0 +1,43 @@
+#![cfg(test)]
+
+use crate::symbol_table::SymbolTable;
+use super::*;
+
+fn build_ir(input: &str) -> ReducedIR {
+  let ast = crate::util::quick_ast(input);
+
+  let mut symbol_table = SymbolTable::new();
+  symbol_table.process_ast(&ast).unwrap();
+
+  let reduced = reduce(&ast, &symbol_table);
+  reduced.debug(&symbol_table);
+  reduced
+}
+
+
+#[test]
+fn test_ir() {
+    let src = r#"
+
+    let global_one = 10 + 20
+    let global_two = "the string hello"
+
+    fn a_function(i, j, k) {
+        fn nested(x) {
+            x + 10
+        }
+        i + j * nested(k)
+    }
+
+    fn another_function(e) {
+        let local_var = 420
+        e * local_var
+    }
+
+    another_function()
+    "#;
+
+    let reduced = build_ir(src);
+    assert_eq!(reduced.functions.len(), 3);
+    //assert!(1 == 2);
+}

schala-lang/language/src/reduced_ir/types.rs

@@ -0,0 +1,162 @@
+use std::collections::HashMap;
+use std::rc::Rc;
+use std::convert::From;
+
+use crate::builtin::Builtin;
+use crate::symbol_table::{DefId, SymbolTable};
+use crate::typechecking::TypeId;
+
+//TODO most of these Clone impls only exist to support function application, because the
+//tree-walking evaluator moves the reduced IR members.
+
+/// The reduced intermediate representation consists of a list of function definitions, and a block
+/// of entrypoint statements.  In a repl or script context this can be an arbitrary list of
+/// statements, in an executable context will likely just be a pointer to the main() function.
+#[derive(Debug)]
+pub struct ReducedIR {
+    pub functions: HashMap<DefId, FunctionDefinition>,
+    pub entrypoint: Vec<Statement>,
+}
+
+impl ReducedIR {
+    #[allow(dead_code)]
+    pub fn debug(&self, symbol_table: &SymbolTable) {
+        println!("Reduced IR:");
+        println!("Functions:");
+        println!("-----------");
+        for (id, callable) in self.functions.iter() {
+            let name = &symbol_table.lookup_symbol_by_def(id).unwrap().local_name();
+            println!("{}({}) -> {:?}", id, name, callable);
+        }
+        println!("");
+        println!("Entrypoint:");
+        println!("-----------");
+        for stmt in self.entrypoint.iter() {
+            println!("{:?}", stmt);
+        }
+        println!("-----------");
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum Statement {
+    Expression(Expression),
+    Binding {
+        id: DefId,
+        constant: bool,
+        expr: Expression
+    },
+}
+
+#[derive(Debug, Clone)]
+pub enum Expression {
+    Literal(Literal),
+    Tuple(Vec<Expression>),
+    Lookup(Lookup),
+    Assign {
+        lval: DefId,
+        rval: Box<Expression>,
+    },
+    Callable(Callable),
+    Call {
+        f: Box<Expression>,
+        args: Vec<Expression>
+    },
+    Conditional {
+        cond: Box<Expression>,
+        then_clause: Vec<Statement>,
+        else_clause: Vec<Statement>,
+    },
+    CaseMatch {
+        cond: Box<Expression>,
+        alternatives: Vec<Alternative>,
+    },
+    ReductionError(String),
+}
+
+impl Expression {
+    pub fn unit() -> Self {
+        Expression::Tuple(vec![])
+    }
+}
+
+#[derive(Debug)]
+pub struct FunctionDefinition {
+    pub body: Vec<Statement>
+}
+
+#[derive(Debug, Clone)]
+pub enum Callable {
+    Builtin(Builtin),
+    UserDefined(DefId),
+    Lambda {
+        arity: u8,
+        body: Vec<Statement>
+    },
+    DataConstructor {
+        type_id: TypeId,
+        arity: u32,
+        tag: u32
+    },
+}
+
+#[derive(Debug, Clone)]
+pub enum Lookup {
+    LocalVar(DefId),
+    GlobalVar(DefId),
+    Function(DefId),
+    Param(u8),
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum Literal {
+    Nat(u64),
+    Int(i64),
+    Float(f64),
+    Bool(bool),
+    StringLit(Rc<String>),
+}
+
+#[derive(Debug, Clone)]
+pub struct Alternative {
+    pub pattern: Pattern,
+    pub item: Vec<Statement>,
+}
+
+#[derive(Debug, Clone)]
+pub enum Pattern {
+    Tuple {
+        subpatterns: Vec<Pattern>,
+        tag: Option<u32>,
+    },
+    Literal(Literal),
+    Ignored,
+    Binding(DefId)
+}
+
+/*
+#[derive(Debug, Clone)]
+pub struct Subpattern {
+    pub tag: Option<usize>,
+    pub subpatterns: Vec<Option<Subpattern>>,
+    //pub bound_vars: BoundVars,
+    pub guard: Option<Expression>,
+}
+*/
+
+#[derive(Debug)]
+pub struct PatternError {
+    msg: String,
+}
+
+impl From<&str> for PatternError {
+    fn from(s: &str) -> Self {
+        Self { msg: s.to_string() }
+    }
+}
+
+impl From<String> for PatternError {
+    fn from(msg: String) -> Self {
+        Self { msg }
+    }
+}

schala-lang/language/src/schala.rs

@@ -1,26 +1,31 @@
 use stopwatch::Stopwatch;
 
 use crate::error::SchalaError;
-use crate::{eval, parsing, reduced_ast, symbol_table, tokenizing, typechecking};
+use crate::{/*eval, */parsing, reduced_ir, tree_walk_eval, symbol_table, tokenizing, typechecking};
 use schala_repl::{
     ComputationRequest, ComputationResponse, GlobalOutputStats, LangMetaRequest, LangMetaResponse,
     ProgrammingLanguageInterface,
 };
 
 /// All the state necessary to parse and execute a Schala program are stored in this struct.
-pub struct Schala {
+pub struct Schala<'a> {
     /// Holds a reference to the original source code, parsed into line and character
     source_reference: SourceReference,
-    /// Execution state for AST-walking interpreter
+
-    state: eval::State<'static>,
+    //state: eval::State<'static>,
     /// Keeps track of symbols and scopes
     symbol_table: symbol_table::SymbolTable,
     /// Contains information for type-checking
     type_context: typechecking::TypeContext<'static>,
     /// Schala Parser
     active_parser: parsing::Parser,
+
+    /// Execution state for AST-walking interpreter
+    eval_state: tree_walk_eval::State<'a>,
+
 }
 
+/*
 impl Schala {
     //TODO implement documentation for language items
     /*
@@ -31,23 +36,25 @@ impl Schala {
     }
     */
 }
+*/
 
-impl Schala {
+impl<'a> Schala<'a> {
     /// Creates a new Schala environment *without* any prelude.
-    fn new_blank_env() -> Schala {
+    fn new_blank_env() -> Schala<'a> {
         Schala {
             source_reference: SourceReference::new(),
             symbol_table: symbol_table::SymbolTable::new(),
-            state: eval::State::new(),
+            //state: eval::State::new(),
             type_context: typechecking::TypeContext::new(),
             active_parser: parsing::Parser::new(),
+            eval_state: tree_walk_eval::State::new(),
         }
     }
 
     /// Creates a new Schala environment with the standard prelude, which is defined as ordinary
     /// Schala code in the file `prelude.schala`
     #[allow(clippy::new_without_default)]
-    pub fn new() -> Schala {
+    pub fn new() -> Schala<'a> {
         let prelude = include_str!("../source-files/prelude.schala");
         let mut env = Schala::new_blank_env();
 
@@ -88,6 +95,22 @@ impl Schala {
             .typecheck(&ast)
             .map_err(SchalaError::from_type_error);
 
+        let reduced_ir = reduced_ir::reduce(&ast, &self.symbol_table);
+        println!("Reduced IR: {:?}", reduced_ir);
+
+        let evaluation_outputs = self.eval_state.evaluate(reduced_ir, true);
+        let text_output: Result<Vec<String>, String> = evaluation_outputs.into_iter().collect();
+
+        let text_output: Result<Vec<String>, SchalaError> =
+            text_output.map_err(|err| SchalaError::from_string(err, Stage::Evaluation));
+
+        let eval_output: String =
+            text_output.map(|v| Iterator::intersperse(v.into_iter(), "\n".to_owned()).collect())?;
+
+        Ok(eval_output)
+
+        /*
+
         // Reduce AST - TODO this doesn't produce an error yet, but probably should
         let reduced_ast = reduced_ast::reduce(&ast, &self.symbol_table);
 
@@ -102,6 +125,7 @@ impl Schala {
             text_output.map(|v| Iterator::intersperse(v.into_iter(), "\n".to_owned()).collect())?;
 
         Ok(eval_output)
+        */
     }
 }
 
@@ -151,7 +175,7 @@ fn stage_names() -> Vec<&'static str> {
     ]
 }
 
-impl ProgrammingLanguageInterface for Schala {
+impl<'a> ProgrammingLanguageInterface for Schala<'a> {
     //TODO flesh out Config
     type Config = ();
     fn language_name() -> String {

schala-lang/language/src/symbol_table/mod.rs

@@ -8,13 +8,49 @@ use crate::ast::{
     Variant, VariantKind,
 };
 use crate::tokenizing::Location;
-use crate::typechecking::TypeName;
+use crate::typechecking::TypeId;
 
 mod resolver;
 mod symbol_trie;
 use symbol_trie::SymbolTrie;
 mod test;
 
+
+//TODO parameterize different types of ID
+/// ID used for definitions
+#[derive(Debug, PartialEq, Eq, Hash, Clone, Default)]
+pub struct DefId {
+  idx: u32,
+}
+
+impl DefId {
+  pub fn as_u32(&self) -> u32 {
+      self.idx
+  }
+}
+
+impl fmt::Display for DefId {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "DefId:{}", self.idx)
+  }
+}
+
+pub struct DefIdStore {
+  last_idx: u32
+}
+
+impl DefIdStore {
+  pub fn new() -> Self {
+    Self { last_idx: 0 }
+  }
+
+  pub fn fresh(&mut self) -> DefId {
+    let idx = self.last_idx;
+    self.last_idx += 1;
+    DefId { idx }
+  }
+}
+
 /// Fully-qualified symbol name
 #[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
 pub struct Fqsn {
@@ -47,6 +83,19 @@ impl Fqsn {
     }
 }
 
+impl fmt::Display for Fqsn {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let delim = "::";
+        let Fqsn { scopes } = self;
+        write!(f, "FQSN<{}", scopes[0])?;
+        for item in scopes[1..].iter() {
+            write!(f, "{}{}", delim, item)?;
+        }
+        write!(f, ">")
+    }
+}
+
+
 //TODO eventually this should use ItemId's to avoid String-cloning
 /// One segment within a scope.
 #[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
@@ -54,6 +103,13 @@ enum Scope {
     Name(Rc<String>),
 }
 
+impl fmt::Display for Scope {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let Scope::Name(name) = self;
+        write!(f, "{}", name)
+    }
+}
+
 #[allow(dead_code)]
 #[derive(Debug, Clone)]
 pub enum SymbolError {
@@ -113,6 +169,9 @@ impl<K> NameTable<K> {
 
 //cf. p. 150 or so of Language Implementation Patterns
 pub struct SymbolTable {
+
+    def_id_store: DefIdStore,
+
     /// Used for import resolution.
     symbol_trie: SymbolTrie,
 
@@ -131,6 +190,7 @@ pub struct SymbolTable {
 impl SymbolTable {
     pub fn new() -> SymbolTable {
         SymbolTable {
+            def_id_store: DefIdStore::new(),
             symbol_trie: SymbolTrie::new(),
             fq_names: NameTable::new(),
             types: NameTable::new(),
@@ -148,67 +208,112 @@ impl SymbolTable {
         if !errs.is_empty() {
             return Err(errs);
         }
-        self.resolve_symbol_ids(ast);
+        self.resolve_scopes(ast);
         Ok(())
     }
 
     pub fn lookup_symbol(&self, id: &ItemId) -> Option<&Symbol> {
         self.id_to_symbol.get(id).map(|s| s.as_ref())
     }
+
+    //TODO optimize this
+    pub fn lookup_symbol_by_def(&self, def: &DefId) -> Option<&Symbol> {
+        self.id_to_symbol.iter().find(|(_, sym)| sym.def_id == *def)
+            .map(|(_, sym)| sym.as_ref())
+    }
+
+    #[allow(dead_code)]
+    pub fn debug(&self) {
+        println!("Symbol table:");
+        println!("----------------");
+        for (id, sym) in self.id_to_symbol.iter() {
+            println!("{} => {}", id, sym);
+        }
+    }
 }
 
 #[allow(dead_code)]
 #[derive(Debug, Clone)]
 pub struct Symbol {
-    pub local_name: Rc<String>,
     fully_qualified_name: Fqsn,
-    pub spec: SymbolSpec,
+    spec: SymbolSpec,
+    def_id: DefId,
+}
+
+impl Symbol {
+    pub fn local_name(&self) -> Rc<String> {
+        self.fully_qualified_name.local_name()
+    }
+
+    pub fn def_id(&self) -> Option<DefId> {
+        Some(self.def_id.clone())
+    }
+
+    pub fn spec(&self) -> SymbolSpec {
+        self.spec.clone()
+    }
 }
 
 impl fmt::Display for Symbol {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "<Local name: {}, Spec: {}>", self.local_name, self.spec)
+        write!(f, "<Local name: {}, {}, Spec: {}>", self.local_name(), self.fully_qualified_name, self.spec)
     }
 }
 
+//TODO - I think I eventually want to draw a distinction between true global items
+//i.e. global vars, and items whose definitions are scoped. Right now there's a sense
+//in which Func, DataConstructor, RecordConstructor, and GlobalBinding are "globals",
+//whereas LocalVarible and FunctionParam have local scope. But right now, they all
+//get put into a common table, and all get DefId's from a common source.
+//
+//It would be good if individual functions could in parallel look up their own
+//local vars without interfering with other lookups. Also some type definitions
+//should be scoped in a similar way.
+//
+//Also it makes sense that non-globals should not use DefId's, particularly not
+//function parameters (even though they are currently assigned).
 #[derive(Debug, Clone)]
 pub enum SymbolSpec {
-    Func(Vec<TypeName>),
+    Func,
     DataConstructor {
         index: usize,
         arity: usize,
-        type_name: TypeName, //TODO this eventually needs to be some kind of ID
+        type_id: TypeId,
     },
     RecordConstructor {
         index: usize,
-        members: HashMap<Rc<String>, TypeName>,
+        members: HashMap<Rc<String>, TypeId>,
-        type_name: TypeName,
+        type_id: TypeId,
     },
-    Binding,
+    GlobalBinding, //Only for global variables, not for function-local ones or ones within a `let` scope context
+    LocalVariable,
+    FunctionParam(u8),
 }
 
 impl fmt::Display for SymbolSpec {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         use self::SymbolSpec::*;
         match self {
-            Func(type_names) => write!(f, "Func({:?})", type_names),
+            Func => write!(f, "Func"),
             DataConstructor {
                 index,
-                type_name,
+                type_id,
                 arity,
             } => write!(
                 f,
                 "DataConstructor(idx: {}, arity: {}, type: {})",
-                index, arity, type_name
+                index, arity, type_id
             ),
             RecordConstructor {
-                type_name, index, ..
+                type_id, index, ..
             } => write!(
                 f,
                 "RecordConstructor(idx: {})(<members> -> {})",
-                index, type_name
+                index, type_id
             ),
-            Binding => write!(f, "Binding"),
+            GlobalBinding => write!(f, "GlobalBinding"),
+            LocalVariable => write!(f, "Local variable"),
+            FunctionParam(n) => write!(f, "Function param: {}", n),
         }
     }
 }
@@ -220,11 +325,13 @@ impl SymbolTable {
     /// Register a new mapping of a fully-qualified symbol name (e.g. `Option::Some`)
     /// to a Symbol, a descriptor of what that name refers to.
     fn add_symbol(&mut self, id: &ItemId, fqsn: Fqsn, spec: SymbolSpec) {
+        let def_id = self.def_id_store.fresh();
         let symbol = Rc::new(Symbol {
-            local_name: fqsn.local_name(),
             fully_qualified_name: fqsn.clone(),
             spec,
+            def_id,
         });
+        println!("In add_symbol(), adding: {:?}", symbol);
         self.symbol_trie.insert(&fqsn);
         self.fqsn_to_symbol.insert(fqsn, symbol.clone());
         self.id_to_symbol.insert(id.clone(), symbol.clone());
@@ -232,8 +339,8 @@ impl SymbolTable {
 
     /// Walks the AST, matching the ID of an identifier used in some expression to
     /// the corresponding Symbol.
-    fn resolve_symbol_ids(&mut self, ast: &ast::AST) {
+    fn resolve_scopes(&mut self, ast: &ast::AST) {
-        let mut resolver = resolver::Resolver::new(self);
+        let mut resolver = resolver::ScopeResolver::new(self);
         resolver.resolve(ast);
     }
 
@@ -243,13 +350,14 @@ impl SymbolTable {
     /// up name tables that will be used by further parts of the compiler
     fn populate_name_tables(&mut self, ast: &ast::AST) -> Vec<SymbolError> {
         let mut scope_stack = vec![];
-        self.add_from_scope(ast.statements.as_ref(), &mut scope_stack)
+        self.add_from_scope(ast.statements.as_ref(), &mut scope_stack, false)
     }
 
     fn add_from_scope<'a>(
         &'a mut self,
         statements: &[Statement],
         scope_stack: &mut Vec<Scope>,
+        function_scope: bool,
     ) -> Vec<SymbolError> {
         let mut errors = vec![];
 
@@ -260,7 +368,7 @@ impl SymbolTable {
                 location,
             } = statement; //TODO I'm not sure if I need to do anything with this ID
             let location = *location;
-            if let Err(err) = self.add_single_statement(id, kind, location, scope_stack) {
+            if let Err(err) = self.add_single_statement(id, kind, location, scope_stack, function_scope) {
                 errors.push(err);
             } else {
                 // If there's an error with a name, don't recurse into subscopes of that name
@@ -268,14 +376,14 @@ impl SymbolTable {
                     StatementKind::Declaration(Declaration::FuncDecl(signature, body)) => {
                         let new_scope = Scope::Name(signature.name.clone());
                         scope_stack.push(new_scope);
-                        let output = self.add_from_scope(body.as_ref(), scope_stack);
+                        let output = self.add_from_scope(body.as_ref(), scope_stack, true);
                         scope_stack.pop();
                         output
                     }
                     StatementKind::Module(ModuleSpecifier { name, contents }) => {
                         let new_scope = Scope::Name(name.clone());
                         scope_stack.push(new_scope);
-                        let output = self.add_from_scope(contents.as_ref(), scope_stack);
+                        let output = self.add_from_scope(contents.as_ref(), scope_stack, false);
                         scope_stack.pop();
                         output
                     }
@@ -299,6 +407,7 @@ impl SymbolTable {
         kind: &StatementKind,
         location: Location,
         scope_stack: &[Scope],
+        function_scope: bool,
     ) -> Result<(), SymbolError> {
         match kind {
             StatementKind::Declaration(Declaration::FuncSig(signature)) => {
@@ -321,7 +430,7 @@ impl SymbolTable {
                 self.add_symbol(
                     id,
                     fq_function,
-                    SymbolSpec::Func(vec![]), //TODO does this inner vec need to exist at all?
+                    SymbolSpec::Func,
                 );
             }
             StatementKind::Declaration(Declaration::FuncDecl(signature, ..)) => {
@@ -345,7 +454,7 @@ impl SymbolTable {
                 self.add_symbol(
                     id,
                     fq_function,
-                    SymbolSpec::Func(vec![]), //TODO does this inner vec need to exist at all?
+                    SymbolSpec::Func,
                 );
             }
             StatementKind::Declaration(Declaration::TypeDecl { name, .. }) => {
@@ -367,11 +476,13 @@ impl SymbolTable {
                         kind: NameKind::Binding,
                     },
                 )?;
-                self.add_symbol(
+                if !function_scope {
-                    id,
+                    self.add_symbol(
-                    fq_binding,
+                        id,
-                    SymbolSpec::Binding,
+                        fq_binding,
-                );
+                        SymbolSpec::GlobalBinding,
+                    );
+                }
             }
             StatementKind::Module(ModuleSpecifier { name, .. }) => {
                 let fq_module = Fqsn::from_scope_stack(scope_stack, name.clone());
@@ -417,13 +528,15 @@ impl SymbolTable {
 
         for (index, variant) in variants.iter().enumerate() {
             let Variant { name, kind, id } = variant;
+            let type_id = TypeId::lookup_name(name.as_ref());
+
             match kind {
                 VariantKind::UnitStruct => {
                     let fq_name = Fqsn::from_scope_stack(scope_stack.as_ref(), name.clone());
                     let spec = SymbolSpec::DataConstructor {
                         index,
                         arity: 0,
-                        type_name: name.clone(),
+                        type_id,
                     };
                     register(id, fq_name, spec);
                 }
@@ -432,7 +545,7 @@ impl SymbolTable {
                     let spec = SymbolSpec::DataConstructor {
                         index,
                         arity: items.len(),
-                        type_name: name.clone(),
+                        type_id,
                     };
                     register(id, fq_name, spec);
                 }
@@ -459,13 +572,13 @@ impl SymbolTable {
 
                     let spec = SymbolSpec::RecordConstructor {
                         index,
-                        type_name: name.clone(),
+                        type_id,
                         members: members
                             .iter()
-                            .map(|(_, _)| {
+                            .map(|(member_name, _type_identifier)| {
                                 (
-                                    Rc::new("DUMMY_FIELD".to_string()),
+                                    member_name.clone(),
-                                    Rc::new("DUMMY_TYPE_ID".to_string()),
+                                    TypeId::lookup_name("DUMMY_TYPE_ID"),
                                 )
                             })
                             .collect(),

schala-lang/language/src/symbol_table/resolver.rs

@@ -1,28 +1,49 @@
 use std::rc::Rc;
 
 use crate::ast::*;
-use crate::symbol_table::{Fqsn, Scope, SymbolTable};
+use crate::symbol_table::{Fqsn, Scope, SymbolTable, SymbolSpec};
 use crate::util::ScopeStack;
 
-type FqsnPrefix = Vec<Scope>;
+#[derive(Debug)]
-
+enum NameType {
-pub struct Resolver<'a> {
+    //TODO eventually this needs to support closures
-    symbol_table: &'a mut super::SymbolTable,
+    Param(u8), //TODO handle implications of functions being limited to 255 params
-    name_scope_stack: ScopeStack<'a, Rc<String>, FqsnPrefix>,
+    LocalVariable(ItemId),
+    Import(Fqsn),
 }
 
-impl<'a> Resolver<'a> {
+#[derive(Debug)]
+enum ScopeType {
+    Function {
+        name: Rc<String>
+    },
+    Lambda,
+    PatternMatch,
+    //TODO add some notion of a let-like scope?
+}
+
+pub struct ScopeResolver<'a> {
+    symbol_table: &'a mut super::SymbolTable,
+    //TODO maybe this shouldn't be a scope stack, b/c the recursion behavior comes from multiple
+    //instances of ScopeResolver
+    lexical_scopes: ScopeStack<'a, Rc<String>, NameType, ScopeType>,
+}
+
+impl<'a> ScopeResolver<'a> {
     pub fn new(symbol_table: &'a mut SymbolTable) -> Self {
-        let name_scope_stack: ScopeStack<'a, Rc<String>, FqsnPrefix> = ScopeStack::new(None);
+        let lexical_scopes = ScopeStack::new(None);
         Self {
             symbol_table,
-            name_scope_stack,
+            lexical_scopes,
         }
     }
+
     pub fn resolve(&mut self, ast: &AST) {
         walk_ast(self, ast);
     }
 
+
+    /*
     fn lookup_name_in_scope(&self, sym_name: &QualifiedName) -> Fqsn {
         let QualifiedName { components, .. } = sym_name;
         let first_component = &components[0];
@@ -45,19 +66,63 @@ impl<'a> Resolver<'a> {
             }
         }
     }
+    */
 
-    fn qualified_name(&mut self, name: &QualifiedName) {
+    /// This method correctly modifies the id_to_symbol table (ItemId) to have the appropriate
-        let fqsn = self.lookup_name_in_scope(name);
+    /// mappings.
-        let symbol = self.symbol_table.fqsn_to_symbol.get(&fqsn);
+    fn lookup_name_in_scope(&mut self, name: &QualifiedName) {
-        if let Some(symbol) = symbol {
+        let QualifiedName { id, components } = name;
-            self.symbol_table.id_to_symbol.insert(name.id.clone(), symbol.clone());
+        //TODO handle a "partial" qualified name, and also handle it down in the pattern-matching
+        //section
+        //TODO some of these if lets that look into the fqsn_to_symbol table should probaby fail
+        //with an error
+        if components.len() == 1 {
+            let local_name: Rc<String> = components[0].clone();
+            let name_type = self.lexical_scopes.lookup(&local_name);
+            match name_type {
+                Some(NameType::Import(fqsn)) => {
+                    let symbol = self.symbol_table.fqsn_to_symbol.get(&fqsn);
+                    if let Some(symbol) = symbol {
+                        self.symbol_table.id_to_symbol.insert(id.clone(), symbol.clone());
+                    }
+                },
+                Some(NameType::Param(n)) => {
+                    let spec = SymbolSpec::FunctionParam(*n);
+                    //TODO need to come up with a better solution for local variable FQSNs
+                    let lscope = Scope::Name(Rc::new("<local-param>".to_string()));
+                    let fqsn = Fqsn { scopes: vec![lscope, Scope::Name(local_name.clone())] };
+                    self.symbol_table.add_symbol(id, fqsn, spec);
+                }
+                Some(NameType::LocalVariable(item_id)) => {
+                    let symbol = self.symbol_table.id_to_symbol.get(&item_id).cloned();
+                    if let Some(symbol) = symbol {
+                        self.symbol_table.id_to_symbol.insert(id.clone(), symbol);
+                    }
+                },
+                None => {
+                    //TODO see if I can reduce this duplicate code
+                    let fqsn = Fqsn { scopes: vec![Scope::Name(local_name.clone())] };
+                    let symbol = self.symbol_table.fqsn_to_symbol.get(&fqsn);
+                    if let Some(symbol) = symbol {
+                        self.symbol_table.id_to_symbol.insert(id.clone(), symbol.clone());
+                    }
+                }
+            }
+        } else {
+            let fqsn = Fqsn { scopes: components.iter().map(|name| Scope::Name(name.clone())).collect() };
+            let symbol = self.symbol_table.fqsn_to_symbol.get(&fqsn);
+            if let Some(symbol) = symbol {
+                self.symbol_table.id_to_symbol.insert(id.clone(), symbol.clone());
+            }
         }
     }
 }
 
-impl<'a> ASTVisitor for Resolver<'a> {
+impl<'a> ASTVisitor for ScopeResolver<'a> {
-    //TODO need to un-insert these - maybe need to rethink visitor
+    // Import statements bring in a bunch of local names that all map to a specific FQSN.
-    fn import(&mut self, import_spec: &ImportSpecifier) {
+    // FQSNs map to a Symbol (or this is an error), Symbols have a DefId. So for every
+    // name we import, we map a local name (a string) to a NameType::ImportedDefinition(DefId).
+    fn import(&mut self, import_spec: &ImportSpecifier) -> Recursion {
         let ImportSpecifier {
             ref path_components,
             ref imported_names,
@@ -72,56 +137,185 @@ impl<'a> ASTVisitor for Resolver<'a> {
                         .collect(),
                 };
                 let members = self.symbol_table.symbol_trie.get_children(&prefix);
-                for member in members.into_iter() {
+                for fqsn in members.into_iter() {
-                    let Scope::Name(n) = member.scopes.last().unwrap();
+                    self.lexical_scopes.insert( fqsn.local_name(), NameType::Import(fqsn));
-                    let local_name = n.clone();
-                    self.name_scope_stack.insert(local_name, member.scopes);
                 }
             }
             ImportedNames::LastOfPath => {
-                let name = path_components.last().unwrap(); //TODO handle better
+                let fqsn = Fqsn {
-                let fqsn_prefix = path_components
+                    scopes: path_components
                     .iter()
                     .map(|c| Scope::Name(c.clone()))
-                    .collect();
+                    .collect()
-                self.name_scope_stack.insert(name.clone(), fqsn_prefix);
+                };
+                self.lexical_scopes.insert(fqsn.local_name(), NameType::Import(fqsn));
             }
             ImportedNames::List(ref names) => {
-                let fqsn_prefix: FqsnPrefix = path_components
+                let fqsn_prefix: Vec<Scope> = path_components
                     .iter()
                     .map(|c| Scope::Name(c.clone()))
                     .collect();
                 for name in names.iter() {
-                    self.name_scope_stack
+                    let mut scopes = fqsn_prefix.clone();
-                        .insert(name.clone(), fqsn_prefix.clone());
+                    scopes.push(Scope::Name(name.clone()));
+                    let fqsn = Fqsn { scopes };
+                    self.lexical_scopes.insert(fqsn.local_name(), NameType::Import(fqsn));
                 }
             }
         };
+        Recursion::Continue
     }
 
-    fn expression(&mut self, expression: &Expression) {
+    fn declaration(&mut self, declaration: &Declaration, id: &ItemId) -> Recursion {
-        use ExpressionKind::*;
+        let cur_function_name = match self.lexical_scopes.get_name() {
-        match &expression.kind {
+            //TODO this needs to be a fqsn
-            Value(name) => {
+            Some(ScopeType::Function { name }) => Some(name.clone()),
-                self.qualified_name(name);
+            _ => None
-            },
+        };
-            NamedStruct { name, fields: _ } => {
+        match declaration {
-                self.qualified_name(name);
+            Declaration::FuncDecl(signature, block) => {
-            },
+                let param_names = signature.params.iter().map(|param| param.name.clone());
-            _ => (),
+                //TODO I'm 90% sure this is right, until I get to closures
+                //let mut new_scope = self.lexical_scopes.new_scope(Some(ScopeType::Function { name: signature.name.clone() }));
+                let mut new_scope = ScopeStack::new(Some(ScopeType::Function { name: signature.name.clone() }));
+
+                for (n, param) in param_names.enumerate().into_iter() {
+                    new_scope.insert(param, NameType::Param(n as u8));
+                }
+
+                let mut new_resolver = ScopeResolver {
+                    symbol_table: self.symbol_table,
+                    lexical_scopes: new_scope,
+                };
+                walk_block(&mut new_resolver, block);
+                Recursion::Stop
+            }
+            Declaration::Binding { name, .. } => {
+                if let Some(fn_name) = cur_function_name {
+                    // We are within a function scope
+                    let fqsn = Fqsn { scopes: vec![Scope::Name(fn_name.clone()), Scope::Name(name.clone())] };
+                    self.symbol_table.add_symbol(id, fqsn, SymbolSpec::LocalVariable);
+                    self.lexical_scopes.insert(name.clone(), NameType::LocalVariable(id.clone()));
+                }
+                Recursion::Continue
+            }
+            _ => Recursion::Continue
         }
     }
 
-    fn pattern(&mut self, pat: &Pattern) {
+    fn expression(&mut self, expression: &Expression) -> Recursion {
+        use ExpressionKind::*;
+        match &expression.kind {
+            Value(name) => {
+                self.lookup_name_in_scope(name);
+            },
+            NamedStruct { name, fields: _ } => {
+                self.lookup_name_in_scope(name);
+            },
+            Lambda { params, body, .. } => {
+                let param_names = params.iter().map(|param| param.name.clone());
+                //TODO need to properly handle closure scope, this is currently broken
+                //let mut new_scope = self.lexical_scopes.new_scope(Some(ScopeType::Function { name: signature.name.clone() }));
+                let mut new_scope = ScopeStack::new(Some(ScopeType::Lambda));
+
+                for (n, param) in param_names.enumerate().into_iter() {
+                    new_scope.insert(param, NameType::Param(n as u8));
+                }
+
+                let mut new_resolver = ScopeResolver {
+                    symbol_table: self.symbol_table,
+                    lexical_scopes: new_scope,
+                };
+                walk_block(&mut new_resolver, body);
+                return Recursion::Stop;
+            }
+            IfExpression { discriminator, body } => {
+                if let Some(d) = discriminator.as_ref() {
+                    walk_expression(self, &d);
+                }
+                let mut resolver = ScopeResolver {
+                    lexical_scopes: self.lexical_scopes.new_scope(Some(ScopeType::PatternMatch)),
+                    symbol_table: self.symbol_table
+                };
+                let new_resolver = &mut resolver;
+
+                match body.as_ref() {
+                    IfExpressionBody::SimpleConditional {
+                        then_case,
+                        else_case,
+                    } => {
+                        walk_block(new_resolver, then_case);
+                        if let Some(block) = else_case.as_ref() {
+                            walk_block(new_resolver, block)
+                        }
+                    }
+                    IfExpressionBody::SimplePatternMatch {
+                        pattern,
+                        then_case,
+                        else_case,
+                    } => {
+                        walk_pattern(new_resolver, pattern);
+                        walk_block(new_resolver, &then_case);
+                        if let Some(ref block) = else_case.as_ref() {
+                            walk_block(new_resolver, &block)
+                        }
+                    }
+                    IfExpressionBody::CondList(arms) => {
+                        for arm in arms {
+                            match arm.condition {
+                                Condition::Pattern(ref pat) => {
+                                    walk_pattern(new_resolver, pat);
+                                }
+                                Condition::TruncatedOp(ref _binop, ref expr) => {
+                                    walk_expression(new_resolver, expr);
+                                }
+                                Condition::Expression(ref expr) => {
+                                    walk_expression(new_resolver, expr);
+                                }
+                                Condition::Else => (),
+                            }
+                            if let Some(ref guard) = arm.guard {
+                                walk_expression(new_resolver, &guard);
+                            }
+                            walk_block(new_resolver, &arm.body);
+                        }
+                    }
+                };
+
+                return Recursion::Stop;
+            },
+            _ => (),
+        }
+        Recursion::Continue
+    }
+
+    fn pattern(&mut self, pat: &Pattern) -> Recursion {
         use Pattern::*;
 
         match pat {
-            //TODO I think not handling TuplePattern is an oversight
+            Literal(..) | Ignored | TuplePattern(..) => (),
-            TuplePattern(_) => (),
+            TupleStruct(name, _) | Record(name, _) => {
-            Literal(_) | Ignored => (),
+                self.lookup_name_in_scope(name);
-            TupleStruct(name, _) | Record(name, _) | VarOrName(name) => {
-                self.qualified_name(name);
             }
+            //TODO this isn't really the right syntax for a VarOrName
+            VarOrName(ref name @ QualifiedName { id, components }) => {
+                if components.len() == 1 {
+                    //TODO need a better way to construct a FQSN from a QualifiedName
+                    let local_name: Rc<String> = components[0].clone();
+                    let lscope = Scope::Name(Rc::new("<local-case-match>".to_string()));
+                    let fqsn = Fqsn { scopes: vec![lscope, Scope::Name(local_name.clone())] };
+                    //let local_name = fqsn.local_name();
+                    self.symbol_table.add_symbol(id, fqsn, SymbolSpec::LocalVariable);
+                    self.lexical_scopes.insert(local_name.clone(), NameType::LocalVariable(id.clone()));
+                } else {
+                    let fqsn = Fqsn { scopes: components.iter().map(|name| Scope::Name(name.clone())).collect() };
+                    let symbol = self.symbol_table.fqsn_to_symbol.get(&fqsn);
+                    if let Some(symbol) = symbol {
+                        self.symbol_table.id_to_symbol.insert(id.clone(), symbol.clone());
+                    }
+                }
+            },
         };
+        Recursion::Continue
     }
 }

schala-lang/language/src/tree_walk_eval/mod.rs

@@ -0,0 +1,471 @@
+use crate::reduced_ir::{ReducedIR, Expression, Lookup, Callable, FunctionDefinition, Statement, Literal, Alternative, Pattern};
+use crate::symbol_table::{DefId};
+use crate::util::ScopeStack;
+use crate::builtin::Builtin;
+use crate::typechecking::TypeId;
+
+use std::fmt::Write;
+use std::rc::Rc;
+use std::convert::From;
+
+mod test;
+
+type EvalResult<T> = Result<T, RuntimeError>;
+
+#[derive(Debug)]
+pub struct State<'a> {
+  environments: ScopeStack<'a, Memory, MemoryValue>,
+}
+
+//TODO - eh, I dunno, maybe it doesn't matter exactly how memory works in the tree-walking
+//evaluator
+#[derive(Debug, PartialEq, Eq, Hash, Clone)]
+enum Memory {
+    Index(u32)
+}
+
+// This is for function param lookups, and is a hack
+impl From<u8> for Memory {
+    fn from(n: u8) -> Self {
+        Memory::Index(4_000_000 + (n as u32))
+    }
+}
+
+impl From<&DefId> for Memory {
+    fn from(id: &DefId) -> Self {
+        Self::Index(id.as_u32())
+    }
+}
+
+#[derive(Debug)]
+struct RuntimeError {
+    msg: String
+}
+
+impl From<String> for RuntimeError {
+    fn from(msg: String) -> Self {
+        Self {
+            msg
+        }
+    }
+}
+
+impl From<&str> for RuntimeError {
+    fn from(msg: &str) -> Self {
+        Self {
+            msg: msg.to_string(),
+        }
+    }
+}
+
+impl RuntimeError {
+    #[allow(dead_code)]
+    fn get_msg(&self) -> String {
+        format!("Runtime error: {}", self.msg)
+    }
+}
+
+fn paren_wrapped(terms: impl Iterator<Item=String>) -> String {
+  let mut buf = String::new();
+  write!(buf, "(").unwrap();
+  for term in terms.map(Some).intersperse(None) {
+    match term {
+      Some(e) => write!(buf, "{}", e).unwrap(),
+      None => write!(buf, ", ").unwrap(),
+    };
+  }
+  write!(buf, ")").unwrap();
+  buf
+}
+
+/// Anything that can be stored in memory; that is, a function definition, or a fully-evaluated
+/// program value.
+#[derive(Debug)]
+enum MemoryValue {
+    Function(FunctionDefinition),
+    Primitive(Primitive),
+}
+
+impl From<Primitive> for MemoryValue {
+    fn from(prim: Primitive) -> Self {
+        Self::Primitive(prim)
+    }
+}
+
+
+impl MemoryValue {
+    fn to_repl(&self) -> String {
+        match self {
+            MemoryValue::Primitive(ref prim) => prim.to_repl(),
+            MemoryValue::Function(..) => "<function>".to_string(),
+        }
+    }
+}
+
+#[derive(Debug)]
+enum RuntimeValue {
+    Expression(Expression),
+    Evaluated(Primitive),
+}
+
+impl From<Expression> for RuntimeValue {
+    fn from(expr: Expression) -> Self {
+        Self::Expression(expr)
+    }
+}
+
+impl From<Primitive> for RuntimeValue {
+    fn from(prim: Primitive) -> Self {
+        Self::Evaluated(prim)
+    }
+}
+
+/// A fully-reduced value
+#[derive(Debug, Clone)]
+enum Primitive {
+    Tuple(Vec<Primitive>),
+    Literal(Literal),
+    Callable(Callable),
+    Object {
+        type_id: TypeId,
+        tag: u32,
+        items: Vec<Primitive>
+    },
+}
+
+impl Primitive {
+    fn to_repl(&self) -> String {
+        match self {
+            Primitive::Object { type_id, items, .. } if items.len() == 0 => format!("{}", type_id.local_name()),
+            Primitive::Object { type_id, items, .. } =>
+                format!("{}{}", type_id.local_name(), paren_wrapped(items.iter().map(|item| item.to_repl()))),
+            Primitive::Literal(lit) => match lit {
+                Literal::Nat(n) => format!("{}", n),
+                Literal::Int(i) => format!("{}", i),
+                Literal::Float(f) => format!("{}", f),
+                Literal::Bool(b) => format!("{}", b),
+                Literal::StringLit(s) => format!("\"{}\"", s),
+            }
+            Primitive::Tuple(terms) => paren_wrapped(terms.iter().map(|x| x.to_repl())),
+            Primitive::Callable(..) => "<some-callable>".to_string(),
+        }
+    }
+
+    fn unit() -> Self {
+        Primitive::Tuple(vec![])
+    }
+}
+
+impl From<Literal> for Primitive {
+    fn from(lit: Literal) -> Self {
+        Primitive::Literal(lit)
+    }
+}
+
+impl<'a> State<'a> {
+    pub fn new() -> Self {
+        Self {
+            environments: ScopeStack::new(Some("global".to_string()))
+        }
+    }
+
+    pub fn evaluate(&mut self, reduced: ReducedIR, repl: bool) -> Vec<Result<String, String>> {
+        let mut acc = vec![];
+
+        for (def_id, function) in reduced.functions.into_iter() {
+            let mem = (&def_id).into();
+            self.environments.insert(mem, MemoryValue::Function(function));
+        }
+
+        for statement in reduced.entrypoint.into_iter() {
+            match self.statement(statement) {
+                Ok(Some(output)) if repl => {
+                    acc.push(Ok(output.to_repl()))
+                },
+                Ok(_) => (),
+                Err(error) => {
+                    acc.push(Err(error.msg));
+                    return acc;
+                }
+            }
+        }
+        acc
+    }
+
+    fn block(&mut self, statements: Vec<Statement>) -> EvalResult<Primitive> {
+        //TODO need to handle breaks, returns, etc.
+        let mut ret = None;
+        for stmt in statements.into_iter() {
+            if let Some(MemoryValue::Primitive(prim)) = self.statement(stmt)? {
+                ret = Some(prim);
+            }
+        }
+        Ok(if let Some(ret) = ret {
+            ret
+        } else {
+            self.expression(Expression::unit())?
+        })
+    }
+
+    fn statement(&mut self, stmt: Statement) -> EvalResult<Option<MemoryValue>> {
+        match stmt {
+            Statement::Binding { ref id, expr, constant: _ } => {
+                println!("eval() binding id: {}", id);
+                let evaluated = self.expression(expr)?;
+                self.environments.insert(id.into(), evaluated.into());
+                Ok(None)
+            },
+            Statement::Expression(expr) => {
+                let evaluated = self.expression(expr)?;
+                Ok(Some(evaluated.into()))
+            }
+        }
+    }
+
+  fn expression(&mut self, expression: Expression) -> EvalResult<Primitive> {
+      Ok(match expression {
+          Expression::Literal(lit) => Primitive::Literal(lit),
+          Expression::Tuple(items) => Primitive::Tuple(items.into_iter().map(|expr| self.expression(expr)).collect::<EvalResult<Vec<Primitive>>>()?),
+          Expression::Lookup(kind) => match kind {
+              Lookup::Function(ref id) => {
+                  let mem = id.into();
+                  match self.environments.lookup(&mem) {
+                      // This just checks that the function exists in "memory" by ID, we don't
+                      // actually retrieve it until `apply_function()`
+                      Some(MemoryValue::Function(_)) => Primitive::Callable(Callable::UserDefined(id.clone())),
+                      x => return Err(format!("Function not found for id: {} : {:?}", id, x).into()),
+                  }
+              },
+              Lookup::Param(n) => {
+                  let mem = n.into();
+                  match self.environments.lookup(&mem) {
+                      Some(MemoryValue::Primitive(prim)) => prim.clone(),
+                      e => return Err(format!("Param lookup error, got {:?}", e).into()),
+                  }
+              },
+              Lookup::LocalVar(ref id) | Lookup::GlobalVar(ref id) => {
+                  let mem = id.into();
+                  match self.environments.lookup(&mem) {
+                      Some(MemoryValue::Primitive(expr)) => expr.clone(),
+                      _ => return Err(format!("Nothing found for local/gloval variable lookup {}", id).into()),
+                  }
+              },
+          },
+          Expression::Assign { ref lval, box rval } => {
+              let mem = lval.into();
+              let evaluated = self.expression(rval)?;
+              self.environments.insert(mem, MemoryValue::Primitive(evaluated));
+              Primitive::unit()
+          },
+          Expression::Call { box f, args } => self.call_expression(f, args)?,
+          Expression::Callable(Callable::DataConstructor { type_id, arity, tag }) if arity == 0 => Primitive::Object {
+              type_id, tag, items: vec![]
+          },
+          Expression::Callable(func) => Primitive::Callable(func),
+          Expression::Conditional { box cond, then_clause, else_clause } => {
+              let cond = self.expression(cond)?;
+              match cond {
+                  Primitive::Literal(Literal::Bool(true)) => self.block(then_clause)?,
+                  Primitive::Literal(Literal::Bool(false)) => self.block(else_clause)?,
+                  v => return Err(format!("Non-boolean value {:?} in if-statement", v).into())
+              }
+          },
+          Expression::CaseMatch { box cond, alternatives } => self.case_match_expression(cond, alternatives)?,
+          Expression::ReductionError(e) => return Err(e.into()),
+      })
+  }
+
+  fn case_match_expression(&mut self, cond: Expression, alternatives: Vec<Alternative>) -> EvalResult<Primitive> {
+      fn matches(scrut: &Primitive, pat: &Pattern, scope: &mut ScopeStack<Memory, MemoryValue>) -> bool {
+          match pat {
+              Pattern::Ignored => true,
+              Pattern::Binding(ref def_id) => {
+                  let mem = def_id.into();
+                  scope.insert(mem, MemoryValue::Primitive(scrut.clone())); //TODO make sure this doesn't cause problems with nesting
+                  true
+              },
+              Pattern::Literal(pat_literal) => if let Primitive::Literal(scrut_literal) = scrut {
+                  pat_literal == scrut_literal
+              } else {
+                  false
+              },
+              Pattern::Tuple { subpatterns, tag } =>  match tag {
+                  None => match scrut {
+                      Primitive::Tuple(items) if items.len() == subpatterns.len() =>
+                          items.iter().zip(subpatterns.iter()).all(|(item, subpat)| matches(item, subpat, scope)),
+                      _ => false //TODO should be a type error
+                  },
+                  Some(pattern_tag) => match scrut {
+                      //TODO should test type_ids for runtime type checking, once those work
+                      Primitive::Object { tag, items, .. } if tag == pattern_tag && items.len() == subpatterns.len() => {
+                          items.iter().zip(subpatterns.iter()).all(|(item, subpat)| matches(item, subpat, scope))
+                      }
+                      _ => false
+                  }
+              }
+          }
+      }
+      let cond = self.expression(cond)?;
+
+      for alt in alternatives.into_iter() {
+          let mut new_scope = self.environments.new_scope(None);
+          if matches(&cond, &alt.pattern, &mut new_scope) {
+              let mut new_state = State {
+                  environments: new_scope
+              };
+
+              return new_state.block(alt.item)
+          }
+      }
+      Err("No valid match in match expression".into())
+  }
+
+  fn call_expression(&mut self, f: Expression, args: Vec<Expression>) -> EvalResult<Primitive> {
+      let func = match self.expression(f)? {
+          Primitive::Callable(func) => func,
+          other => return Err(format!("Trying to call non-function value: {:?}", other).into()),
+      };
+      match func {
+          Callable::Builtin(builtin) => self.apply_builtin(builtin, args),
+          Callable::UserDefined(def_id) => {
+              let mem = (&def_id).into();
+              match self.environments.lookup(&mem) {
+                  Some(MemoryValue::Function(FunctionDefinition { body })) => {
+                      let body = body.clone(); //TODO ideally this clone would not happen
+                      self.apply_function(body, args)
+                  },
+                  e => Err(format!("Error looking up function with id {}: {:?}", def_id, e).into())
+              }
+          },
+          Callable::Lambda { arity, body } => {
+              if arity as usize != args.len() {
+                  return Err(format!("Lambda expression requries {} arguments, only {} provided", arity, args.len()).into());
+              }
+              let body = body.clone(); //TODO again ideally, no cloning here
+              self.apply_function(body, args)
+          }
+          Callable::DataConstructor { type_id, arity, tag } => {
+              if arity as usize != args.len() {
+                  return Err(format!("Constructor expression requries {} arguments, only {} provided", arity, args.len()).into());
+              }
+
+              let mut evaluated_args: Vec<Primitive> = vec![];
+              for arg in args.into_iter() {
+                  evaluated_args.push(self.expression(arg)?);
+              }
+              Ok(Primitive::Object {
+                  type_id,
+                  tag,
+                  items: evaluated_args
+              })
+          }
+      }
+  }
+
+  fn apply_builtin(&mut self, builtin: Builtin, args: Vec<Expression>) -> EvalResult<Primitive> {
+      use Builtin::*;
+      use Literal::*;
+      use Primitive::Literal as Lit;
+
+      let evaled_args: EvalResult<Vec<Primitive>> =
+          args.into_iter().map(|arg| self.expression(arg)).collect();
+      let evaled_args = evaled_args?;
+
+      Ok(match (builtin, evaled_args.as_slice()) {
+          (FieldAccess, /*&[Node::PrimObject { .. }]*/ _) => {
+              return Err("Field access unimplemented".into());
+          }
+          /* builtin functions */
+          (IOPrint, &[ref anything]) => {
+              print!("{}", anything.to_repl());
+              Primitive::Tuple(vec![])
+          },
+          (IOPrintLn, &[ref anything]) => {
+              print!("{}", anything.to_repl());
+              Primitive::Tuple(vec![])
+          },
+          (IOGetLine, &[]) => {
+              let mut buf = String::new();
+              std::io::stdin().read_line(&mut buf).expect("Error readling line in 'getline'");
+              StringLit(Rc::new(buf.trim().to_string())).into()
+          },
+          /* Binops */
+          (binop, &[ref lhs, ref rhs]) => match (binop, lhs, rhs) {
+              // TODO need a better way of handling these literals
+              (Add, Lit(Nat(l)), Lit(Nat(r))) => Nat(l + r).into(),
+              (Add, Lit(Int(l)), Lit(Int(r))) => Int(l + r).into(),
+              (Add, Lit(Nat(l)), Lit(Int(r))) => Int((*l as i64) + (*r as i64)).into(),
+              (Add, Lit(Int(l)), Lit(Nat(r))) => Int((*l as i64) + (*r as i64)).into(),
+              (Concatenate, Lit(StringLit(ref s1)), Lit(StringLit(ref s2))) => StringLit(Rc::new(format!("{}{}", s1, s2))).into(),
+              (Subtract, Lit(Nat(l)), Lit(Nat(r))) => Nat(l - r).into(),
+              (Multiply, Lit(Nat(l)), Lit(Nat(r))) => Nat(l * r).into(),
+              (Divide, Lit(Nat(l)), Lit(Nat(r))) => Float((*l as f64)/ (*r as f64)).into(),
+              (Quotient, Lit(Nat(l)), Lit(Nat(r))) => if *r == 0 {
+                  return Err("Divide-by-zero error".into());
+              } else {
+                  Nat(l / r).into()
+              },
+              (Modulo, Lit(Nat(l)), Lit(Nat(r))) => Nat(l % r).into(),
+              (Exponentiation, Lit(Nat(l)), Lit(Nat(r))) => Nat(l ^ r).into(),
+              (BitwiseAnd, Lit(Nat(l)), Lit(Nat(r))) => Nat(l & r).into(),
+              (BitwiseOr, Lit(Nat(l)), Lit(Nat(r))) => Nat(l | r).into(),
+
+              /* comparisons */
+              (Equality, Lit(Nat(l)), Lit(Nat(r))) => Bool(l == r).into(),
+              (Equality, Lit(Int(l)), Lit(Int(r))) => Bool(l == r).into(),
+              (Equality, Lit(Float(l)), Lit(Float(r))) => Bool(l == r).into(),
+              (Equality, Lit(Bool(l)), Lit(Bool(r))) => Bool(l == r).into(),
+              (Equality, Lit(StringLit(ref l)), Lit(StringLit(ref r))) => Bool(l == r).into(),
+
+              (LessThan, Lit(Nat(l)), Lit(Nat(r))) => Bool(l < r).into(),
+              (LessThan, Lit(Int(l)), Lit(Int(r))) => Bool(l < r).into(),
+              (LessThan, Lit(Float(l)), Lit(Float(r))) => Bool(l < r).into(),
+
+              (LessThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Bool(l <= r).into(),
+              (LessThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Bool(l <= r).into(),
+              (LessThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Bool(l <= r).into(),
+
+              (GreaterThan, Lit(Nat(l)), Lit(Nat(r))) => Bool(l > r).into(),
+              (GreaterThan, Lit(Int(l)), Lit(Int(r))) => Bool(l > r).into(),
+              (GreaterThan, Lit(Float(l)), Lit(Float(r))) => Bool(l > r).into(),
+
+              (GreaterThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Bool(l >= r).into(),
+              (GreaterThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Bool(l >= r).into(),
+              (GreaterThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Bool(l >= r).into(),
+
+              (binop, lhs, rhs) => return Err(format!("Invalid binop expression {:?} {:?} {:?}", lhs, binop, rhs).into()),
+          },
+          (prefix, &[ref arg]) => match (prefix, arg) {
+              (BooleanNot, Lit(Bool(true))) => Bool(false),
+              (BooleanNot, Lit(Bool(false))) => Bool(true),
+              (Negate, Lit(Nat(n))) => Int(-(*n as i64)),
+              (Negate, Lit(Int(n))) => Int(-(*n as i64)),
+              (Negate, Lit(Float(f))) => Float(-(*f as f64)),
+              (Increment, Lit(Int(n))) => Int(*n),
+              (Increment, Lit(Nat(n))) => Nat(*n),
+              _ => return Err("No valid prefix op".into())
+          }.into(),
+          (x, args) => return Err(format!("bad or unimplemented builtin {:?} | {:?}", x, args).into()),
+      })
+  }
+
+  fn apply_function(&mut self, body: Vec<Statement>, args: Vec<Expression>) -> EvalResult<Primitive> {
+      let mut evaluated_args: Vec<Primitive> = vec![];
+      for arg in args.into_iter() {
+          evaluated_args.push(self.expression(arg)?);
+      }
+
+      let mut frame_state = State {
+          environments: self.environments.new_scope(None)
+      };
+
+      for (n, evaled) in evaluated_args.into_iter().enumerate() {
+          let n = n as u8;
+          let mem = n.into();
+          frame_state.environments.insert(mem, MemoryValue::Primitive(evaled));
+      }
+
+      frame_state.block(body)
+  }
+}
+

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

@@ -0,0 +1,330 @@
+#![cfg(test)]
+use test_case::test_case;
+
+use crate::symbol_table::SymbolTable;
+use crate::tree_walk_eval::State;
+
+fn evaluate_input(input: &str) -> Result<String, String> {
+  let ast = crate::util::quick_ast(input);
+  let mut symbol_table = SymbolTable::new();
+  symbol_table.process_ast(&ast).unwrap();
+  let reduced_ir = crate::reduced_ir::reduce(&ast, &symbol_table);
+  reduced_ir.debug(&symbol_table);
+  println!("========");
+  symbol_table.debug();
+  let mut state = State::new();
+  let mut outputs = state.evaluate(reduced_ir, true);
+  outputs.pop().unwrap()
+}
+
+fn eval_assert(input: &str, expected: &str) {
+    assert_eq!(evaluate_input(input), Ok(expected.to_string()));
+}
+
+#[test]
+fn test_basic_eval() {
+  eval_assert("1 + 2", "3");
+  eval_assert("let mut a = 1; a = 2", "()");
+  eval_assert("let mut a = 1; a = a + 2; a", "3");
+}
+
+#[test]
+fn op_eval() {
+  eval_assert("- 13", "-13");
+  eval_assert("10 - 2", "8");
+}
+
+#[test]
+fn function_eval() {
+  eval_assert("fn oi(x) { x + 1 }; oi(4)", "5");
+  eval_assert("fn oi(x) { x + 1 }; oi(1+2)", "4");
+}
+
+#[test]
+fn scopes() {
+  let scope_ok = r#"
+    let a = 20
+    fn haha() {
+      let something = 38
+      let a = 10
+      a
+    }
+    haha()
+    "#;
+
+    eval_assert(scope_ok, "10");
+
+    let scope_ok = r#"
+    let a = 20
+    fn queque() {
+      let a = 10
+      a
+    }
+    a
+    "#;
+    eval_assert(scope_ok, "20");
+}
+
+#[test]
+fn adt_output_1() {
+    let source = r#"
+
+type Option<T> = Some(T) | None
+let a = Option::None
+let b = Option::Some(10)
+(b, a)
+"#;
+    eval_assert(source, "(Some(10), None)");
+}
+
+#[test]
+fn basic_if_statement() {
+  let source = r#"
+    let a = 10
+    let b = 10
+    if a == b then { 69 } else { 420 }
+    "#;
+    eval_assert(source, "69");
+}
+
+#[test]
+fn basic_patterns_1() {
+    let source =r#"
+let x = 10
+let a = if x is 10 then { 255 } else { 256 }
+let b = if 23 is 99 then { 255 } else { 256 }
+let c = if true is false then { 9 } else { 10 }
+let d = if "xxx" is "yyy" then { 20 } else { 30 }
+(a, b, c, d)
+    "#;
+    eval_assert(source, "(255, 256, 10, 30)");
+}
+
+#[test_case("sanchez", "1")]
+#[test_case("mouri", "2")]
+#[test_case("hella", "3")]
+#[test_case("cyrus", "4")]
+fn basic_patterns_2(input: &str, expected: &str) {
+    let mut source = format!(r#"let x = "{}""#, input);
+    source.push_str(r#"
+if x {
+    is "sanchez" then 1
+    is "mouri" then 2
+    is "hella" then 3
+    is _ then 4
+}
+"#);
+    eval_assert(&source, expected);
+}
+
+#[test_case(r#"(45, "panda", false, 2.2)"#, r#""yes""#)]
+#[test_case(r#"(99, "panda", false, -2.45)"#, r#""maybe""#)]
+fn tuple_patterns(input: &str, expected: &str) {
+    let mut source = format!("let x = {}", input);
+    source.push_str(r#"
+if x {
+    is (45, "pablo", _, 28.4) then "no"
+    is (_, "panda", _, 2.2) then "yes"
+    is _ then "maybe"
+}"#);
+
+    eval_assert(&source, expected);
+}
+
+#[test]
+fn if_is_patterns() {
+  let source = r#"
+type Option<T> = Some(T) | None
+let q = "a string"
+let x = Option::Some(9); if x is Option::Some(q) then { q } else { 0 }"#;
+
+  eval_assert(source, "9");
+
+  let source = r#"
+type Option<T> = Some(T) | None
+let q = "a string"
+let outer = 2
+let x = Option::None; if x is Option::Some(q) then { q } else { -2 + outer }"#;
+  eval_assert(source, "0");
+}
+
+#[test]
+fn full_if_matching() {
+    let source = r#"
+type Option<T> = Some(T) | None
+let a = Option::None
+if a { is Option::None then 4, is Option::Some(x) then x }
+    "#;
+    eval_assert(source, "4");
+
+    let source = r#"
+type Option<T> = Some(T) | None
+let sara = Option::Some(99)
+if sara { is Option::None then 1 + 3, is Option::Some(x) then x }
+    "#;
+    eval_assert(source, "99");
+
+    let source = r#"
+let a = 10
+if a { is 10 then "x", is 4 then "y" }
+    "#;
+    eval_assert(source, "\"x\"");
+
+    let source = r#"
+let a = 10
+if a { is 15 then "x", is 10 then "y" }
+    "#;
+    eval_assert(source, "\"y\"");
+}
+
+//TODO - I can probably cut down some of these
+#[test]
+fn string_pattern() {
+    let source = r#"
+let a = "foo"
+if a { is "foo" then "x", is _ then "y" }
+    "#;
+    eval_assert(source, "\"x\"");
+}
+
+#[test]
+fn boolean_pattern() {
+  let source = r#"
+let a = true
+if a {
+  is true then "x",
+  is false then "y"
+}
+"#;
+    eval_assert(source, "\"x\"");
+}
+
+#[test]
+fn boolean_pattern_2() {
+  let source = r#"
+let a = false
+if a { is true then "x", is false then "y" }
+"#;
+    eval_assert(source, "\"y\"");
+}
+
+#[test]
+fn ignore_pattern() {
+  let source = r#"
+type Option<T> = Some(T) | None
+if Option::Some(10) {
+  is _ then "hella"
+}
+"#;
+    eval_assert(source, "\"hella\"");
+}
+
+#[test]
+fn tuple_pattern() {
+  let source = r#"
+if (1, 2) {
+  is (1, x) then x,
+  is _ then 99
+}
+"#;
+    eval_assert(source, "2");
+}
+
+
+#[test]
+fn tuple_pattern_2() {
+  let source = r#"
+if (1, 2) {
+  is (10, x) then x,
+  is (y, x) then x + y
+}
+"#;
+    eval_assert(source, "3");
+}
+
+#[test]
+fn tuple_pattern_3() {
+  let source = r#"
+if (1, 5) {
+  is (10, x) then x,
+  is (1, x) then x
+}
+"#;
+    eval_assert(source, "5");
+}
+
+#[test]
+fn tuple_pattern_4() {
+  let source = r#"
+if (1, 5) {
+  is (10, x) then x,
+  is (1, x) then x,
+}
+"#;
+    eval_assert(source, "5");
+}
+
+
+#[test]
+fn  prim_obj_pattern() {
+  let source = r#"
+type Stuff = Mulch(Nat) | Jugs(Nat, String) | Mardok
+let a = Stuff::Mulch(20)
+let b = Stuff::Jugs(1, "haha")
+let c = Stuff::Mardok
+
+let x = if a {
+  is Stuff::Mulch(20) then "x",
+  is _ then "ERR"
+}
+
+let y = if b {
+  is Stuff::Mulch(n) then "ERR",
+  is Stuff::Jugs(2, _) then "ERR",
+  is Stuff::Jugs(1, s) then s,
+  is _ then "ERR",
+}
+
+let z = if c {
+  is Stuff::Jugs(_, _) then "ERR",
+  is Stuff::Mardok then "NIGH",
+  is _ then "ERR",
+}
+
+(x, y, z)
+"#;
+    eval_assert(source, r#"("x", "haha", "NIGH")"#);
+}
+
+#[test]
+fn basic_lambda_evaluation_1() {
+    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)
+"#;
+
+eval_assert(source, r"(10, 6)");
+}
+
+#[test]
+fn basic_lambda_evaluation_2() {
+  let source = r#"
+fn milta() {
+  \(x) { x + 33 }
+}
+milta()(10)
+  "#;
+
+  eval_assert(source, "43");
+  }
+
+#[test]
+fn import_all() {
+  let source = r#"
+type Option<T> = Some(T) | None
+import Option::*
+let x = Some(9); if x is Some(q) then { q } else { 0 }"#;
+  eval_assert(source, "9");
+}

schala-lang/language/src/typechecking.rs

@@ -1,5 +1,6 @@
 use std::rc::Rc;
 use std::convert::TryFrom;
+use std::fmt;
 
 use ena::unify::{UnifyKey, InPlaceUnificationTable, UnificationTable, EqUnifyValue};
 
@@ -21,7 +22,31 @@ impl TypeData {
   }
 }
 
-pub type TypeName = Rc<String>;
+//TODO need to hook this into the actual typechecking system somehow
+#[derive(Debug, Clone)]
+pub struct TypeId {
+    local_name: Rc<String>
+}
+
+impl TypeId {
+    //TODO this is definitely incomplete
+    pub fn lookup_name(name: &str) -> TypeId {
+        TypeId {
+            local_name: Rc::new(name.to_string())
+        }
+    }
+
+    pub fn local_name(&self) -> &str {
+        self.local_name.as_ref()
+    }
+}
+
+impl fmt::Display for TypeId {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "TypeId:{}", self.local_name)
+  }
+}
+
 
 pub struct TypeContext<'a> {
   variable_map: ScopeStack<'a, Rc<String>, Type>,

schala-lang/language/src/util.rs

@@ -41,6 +41,7 @@ impl<'a, T, V, N> ScopeStack<'a, T, V, N> where T: Hash + Eq {
     }
   }
 
+  #[allow(dead_code)]
   pub fn lookup_with_scope(&self, key: &T) -> Option<(&V, Option<&N>)> where T: Hash + Eq {
       match (self.values.get(key), self.parent) {
           (None, None) => None,
@@ -49,7 +50,6 @@ impl<'a, T, V, N> ScopeStack<'a, T, V, N> where T: Hash + Eq {
       }
   }
 
-  #[allow(dead_code)]
   pub fn get_name(&self) -> Option<&N> {
     self.scope_name.as_ref()
   }