From a90fdb63e8adb09dafcc050344c443d3b73838bc Mon Sep 17 00:00:00 2001
From: David Li <li.davidm96@gmail.com>
Date: Mon, 6 Nov 2017 21:12:56 -0500
Subject: Parse and typecheck function calls

---
 src/ast.rs                |  1 +
 src/semantic/translate.rs | 49 ++++++++++++++++++++++++++++++++++++++++++++---
 src/semantic/types.rs     |  1 +
 src/taiga.lalrpop         | 17 ++++++++++++++++
 4 files changed, 65 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/ast.rs b/src/ast.rs
index 447c249..f40c66b 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -85,6 +85,7 @@ pub enum Expression {
     Number(u64),
     String(String),
     Name(String),
+    Call(String, Vec<WithLocation<Expression>>),
     Nil,
 }
 
diff --git a/src/semantic/translate.rs b/src/semantic/translate.rs
index 617c832..a5a9557 100644
--- a/src/semantic/translate.rs
+++ b/src/semantic/translate.rs
@@ -10,6 +10,10 @@ use super::types::{self, Ty};
 #[derive(Debug)]
 pub enum TypeError {
     Unimplemented,
+    LengthMismatch {
+        expected: usize,
+        actual: usize,
+    },
     Mismatch {
         expected: Ty,
         actual: Ty,
@@ -71,9 +75,11 @@ fn trans_decl<'a>(
 
             let mut new_venv = TypeEnvironment::new(Some(venv));
             let mut new_tenv = TypeEnvironment::new(Some(tenv));
+            let mut arg_types = vec![];
             for param in params.iter() {
-                let decl_ty = trans_ty(&mut new_venv, &mut new_tenv, &param.ty)?;
-                new_venv.add_binding(param.name.value.clone(), decl_ty);
+                let arg_ty = trans_ty(&mut new_venv, &mut new_tenv, &param.ty)?;
+                arg_types.push(arg_ty.clone());
+                new_venv.add_binding(param.name.value.clone(), arg_ty);
             }
 
             let body_ty = trans_exp(&mut new_venv, &mut new_tenv, &*body)?;
@@ -87,7 +93,7 @@ fn trans_decl<'a>(
                 }
             }
 
-            Ok(body_ty)
+            Ok(Ty::Function(arg_types, Box::new(body_ty)))
         }
         ast::DeclarationBody::Ty { ref ty } => {
             trans_ty(venv, tenv, ty)
@@ -131,6 +137,43 @@ fn trans_exp<'a>(
             }
             trans_exp(&mut new_venv, &mut new_tenv, &*body)
         },
+        &Call(ref name, ref args) => {
+            let mut arg_types = vec![];
+            for arg in args {
+                arg_types.push(trans_exp(venv, tenv, arg)?);
+            }
+
+            let fun_ty = venv.lookup(name)
+                .ok_or(WithLocation::new(TypeError::UnboundName,
+                                         exp.start, exp.end))?;
+            match fun_ty {
+                &Ty::Function(ref expected_args, ref result) => {
+                    if expected_args.len() != arg_types.len() {
+                        return err!(exp, TypeError::LengthMismatch {
+                            expected: expected_args.len(),
+                            actual: arg_types.len(),
+                        });
+                    }
+                    for (i, (provided_ty, expected_ty)) in
+                        arg_types.iter().zip(expected_args).enumerate() {
+                        if provided_ty != expected_ty {
+                            return err!(args[i], TypeError::Mismatch {
+                                expected: expected_ty.clone(),
+                                actual: provided_ty.clone(),
+                            })
+                        }
+                    }
+                    Ok((**result).clone())
+                },
+                otherwise => {
+                    err!(exp, TypeError::Mismatch {
+                        // TODO: better way to handle this
+                        expected: Ty::Function(arg_types, Box::new(Ty::Nil)),
+                        actual: otherwise.clone(),
+                    })
+                }
+            }
+        },
         &UnaryOp(ref op, ref operand) => {
             use ast::UnaryOp::*;
             let operand_ty = trans_exp(venv, tenv, operand)?;
diff --git a/src/semantic/types.rs b/src/semantic/types.rs
index 25d9fb5..928d8c9 100644
--- a/src/semantic/types.rs
+++ b/src/semantic/types.rs
@@ -10,6 +10,7 @@ pub enum Ty {
     Nil,
     Unit,
     Record(Vec<RecordField>),
+    Function(Vec<Ty>, Box<Ty>),
 }
 
 #[derive(Clone,Debug,Eq,PartialEq)]
diff --git a/src/taiga.lalrpop b/src/taiga.lalrpop
index 40830c6..9aa2f38 100644
--- a/src/taiga.lalrpop
+++ b/src/taiga.lalrpop
@@ -136,10 +136,27 @@ ExpressionSign: Box<ast::WithLocation<ast::Expression>> = {
     <ExpressionBase> => <>,
 };
 
+CallArgsList: Vec<WithLocation<ast::Expression>> = {
+    <exp: Expression> "," <rest: CallArgsList> => {
+        let mut rest = rest;
+        rest.push(*exp);
+        rest
+    },
+    <exp: Expression> "," => vec![*exp],
+    <exp: Expression> => vec![*exp],
+};
+
+CallArgs: Vec<WithLocation<ast::Expression>> = {
+    "(" <v: CallArgsList> ")" => v,
+    "(" ")" => vec![],
+};
+
 ExpressionBase: Box<ast::WithLocation<ast::Expression>> = {
     Num => Box::new(<>.map(|v| ast::Expression::Number(v))),
     String => Box::new(<>.map(|v| ast::Expression::String(v))),
     Name => Box::new(<>.map(|v| ast::Expression::Name(v))),
+    <l: @L> <func: Name> <args: CallArgs> <r: @R> =>
+        Box::new(WithLocation::new(ast::Expression::Call(func.value, args), l, r)),
     Spanned<r"nil"> => Box::new(<>.map(|v| ast::Expression::Nil)),
     <l: @L> "let" <d: DeclarationsList> "in" <e: Expression> "end" <r: @R> =>
         Box::new(WithLocation::new(ast::Expression::Let(d, e), l, r)),
-- 
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