working on presentation

diff --git a/deliverables/p2/p2.tex b/deliverables/p2/p2.tex
index 09d75d2..a3fca20 100644 (file)
--- a/deliverables/p2/p2.tex
+++ b/deliverables/p2/p2.tex
@@ -130,7 +130,6 @@ flop(n, l) :: Int -> [Int] -> Bool {
        \begin{itemize}
                \item Mutual recursion is allowed and type checked, however inference is
                not complete.
-               \pause
                \begin{CleanCode}
 flip(n, l) {
   if( n <= 0 ) {return l;} 
@@ -165,6 +164,36 @@ flop(n, l) :: Int -> [Int] -> HSWdn {
        \end{itemize}
 \end{frame}
 
+\begin{frame}[fragile]
+       \frametitle{But wait, there is more!}
+       \framesubtitle{Trouble that is}
+       \begin{itemize}
+               \item Polymorphism is not working great either.
+               \begin{CleanCode}
+id(x) :: a -> a {
+    return x;    
+}
+               \end{CleanCode}
+               \pause
+               \item Is typed fun, but when we introduce: 
+               \begin{CleanCode}
+var x = id(5);
+var y = id(True);
+               \end{CleanCode}
+               \pause
+               \begin{CleanCode}
+2:12 SemError: Cannot unify types. Expected: Int. Given: Bool
+               \end{CleanCode}
+       \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+       \frametitle{But wait, there is more!}
+       \framesubtitle{Trouble that is}
+       
+       \begin
+\end{frame}
+
 % - Can functions that are defined later in a file call earlier defined functions?
 % - Can local variables be defined in terms of other local variables?
 % - How do you deal with assignments?

diff --git a/sem.icl b/sem.icl
index 3438810..06200b1 100644 (file)
--- a/sem.icl
+++ b/sem.icl
@@ -59,25 +59,19 @@ semFunDecl fd=:(FunDecl p f args mt vds stmts) =
        matchFunctions args ft >>= \tres->
     mapM semVarDecl vds >>= \newvds->
     mapM (checkStmt tres) stmts >>= \newstmts->
-       inferReturnType stmts >>= \returntype->
        case mt of
-               Nothing = reconstructType args tres
+               Nothing = inferReturnType stmts
+                       >>= \returntype->reconstructType args tres 
                        >>= \ftype->restoreGamma gamma 
                        >>| putIdent f ftype >>| pure (
                        FunDecl p f args (Just ftype) newvds newstmts)
-               Just t = restoreGamma gamma >>| updateFunType t returntype
-                       >>= \tt-> pure (FunDecl p f args (Just tt) newvds newstmts) 
-
-updateFunType :: Type Type -> Env Type
-updateFunType t1 t2 = unify t1 t2
-updateFunType (t1 ->> t2) t3 = t1 ->> (updateFunType t2 t3)
+               Just t = restoreGamma gamma 
+                       >>| pure (FunDecl p f args mt newvds newstmts) 
 
 inferReturnType :: [Stmt] -> Env Type
 inferReturnType [] = pure VoidType
-inferReturnType [ReturnStmt (Just t):rest] = typeExpr t 
-       >>= \tx->inferReturnType rest >>= \ty->unify tx ty
-inferReturnType [ReturnStmt _:rest] = 
-       inferReturnType rest >>= \tx-> unify VoidType tx
+inferReturnType [ReturnStmt (Just t):rest] = typeExpr t
+inferReturnType [ReturnStmt _:rest] = pure VoidType
 inferReturnType [_:rest] = inferReturnType rest
 
 reconstructType :: [String] Type -> Env Type
@@ -206,8 +200,6 @@ instance unify Type where
     unify (ListType t1) (ListType t2) = unify t1 t2 >>| (pure $ ListType t1)
     unify (ta1 ->> ta2) (tb1 ->> tb2) = unify ta1 tb1 >>= \ta-> unify ta2 tb2 
         >>= \tb-> pure (ta ->> tb)
-    unify VoidType t = pure t
-    unify t VoidType = pure t
     unify VoidType VoidType = pure VoidType
        unify t1 t2 = liftT $ Left $ UnifyError zero t1 t2