From 9254ff63648d9a6f4b058c0a53438db7b60a28cd Mon Sep 17 00:00:00 2001
From: Michael Andreen <harv@ruin.nu>
Date: Sat, 11 Mar 2006 13:30:43 +0000
Subject: [PATCH] typechecking of functions added, not function calls yet
 though

---
 Typecheck.hs   | 27 ++++++++++++++++++++++++---
 Typechecker.hs |  2 +-
 examples/func  |  2 +-
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/Typecheck.hs b/Typecheck.hs
index 29008bd..1814650 100644
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -1,15 +1,15 @@
-module Typecheck where -- (typeCheckExp, typeCheckStm, typeCheckVar, State) where 
+module Typecheck (typeCheckExp, typeCheckStm, typeCheckVar, typeCheckFunction, addFunction, State(..)) where 
 
 
 import Abssyntax
 import Control.Monad.State hiding (State)
-import Data.Map as Map
+import Data.Map as Map hiding (map)
 import Prelude hiding (lookup)
 
 type Types = [Map Ident Type]
 type Function = (Type, [Type])
 
-data State = State {variables::Types,functions::[Map Ident Function],function::Ident}
+data State = State {variables::Types,functions::(Map Ident Function),function::Ident}
 
 
 inList :: Eq a => a -> [a] -> Bool
@@ -87,6 +87,12 @@ typeCheckStm (SDecl t i e) = do
 typeCheckStm (SPrint e) = do
 	typeCheckExp e
 	return ()
+typeCheckStm (SReturn e) = do
+	t <- typeCheckExp e
+	state <- get
+	(t2,_) <- lookup (function state) $ functions state
+	assert (t == t2) $ "Illegal to return "++show t++" in function "++show (function state)++" which returns "++show t2
+
 
 addVariable :: (MonadState State m) => Ident -> Type -> m ()
 addVariable i t = do
@@ -94,3 +100,18 @@ addVariable i t = do
 	let (m:ms) = variables s in case insertLookupWithKey (\k a1 a2 -> a1) i t m of
 		(Nothing,m') -> modify (\s -> s{ variables = m':ms})
 		_ -> fail $ "Duplicate variable declaration: "++show i
+
+typeCheckFunction :: (MonadState State m) => Func -> m ()
+typeCheckFunction (Func t i d s) = do
+	state <- get
+	modify (\s -> s{variables=[empty], function=i})
+	mapM (\(Decl t i) -> addVariable i t) d
+	mapM typeCheckStm s
+	put state
+
+addFunction :: (MonadState State m) => Func -> m ()
+addFunction (Func t i d _) = do
+	s <- get
+	let m = functions s in case insertLookupWithKey (\k a1 a2 -> a1) i (t, map (\(Decl t i) -> t) d) m of
+		(Nothing,m') -> modify (\s -> s{ functions = m'})
+		_ -> fail $ "Duplicate variable declaration: "++show i
diff --git a/Typechecker.hs b/Typechecker.hs
index 8828fbe..71810e6 100644
--- a/Typechecker.hs
+++ b/Typechecker.hs
@@ -45,7 +45,7 @@ run v p s = let ts = myLLexer s in case p ts of
 	Ok (Program s) -> let (fun,st) = splitFunStm (s) in do
 		putStrLn "\nParse Successful!"
 		showTree v (Program s)
-		runStateT (mapM typeCheckStm st) State{variables=[empty], functions=[empty], function=(Ident "")}
+		runStateT (do mapM addFunction fun; mapM typeCheckFunction fun; mapM typeCheckStm st) State{variables=[empty], functions=(empty), function=(Ident "")}
 		print "The program is type-correct!!"
 		return ()
 
diff --git a/examples/func b/examples/func
index fcebceb..4abaa7e 100644
--- a/examples/func
+++ b/examples/func
@@ -8,5 +8,5 @@ int fac(int n){
 	n++;
 	int sum = 1;
 	while (n-- > 1) sum = sum * n;
-	return n;
+	return sum;
 }
-- 
2.39.2