X-Git-Url: http://git.tomasm.cz/fp.git/blobdiff_plain/afc027ed2ff6fdf1aba286c4b6501ee240e36183..763aa13445f67ffe289fe6f3186dd269a909d8a5:/src/HM.hs?ds=sidebyside

diff --git a/src/HM.hs b/src/HM.hs
index 9c4aa76..e643938 100644
--- a/src/HM.hs
+++ b/src/HM.hs
@@ -16,7 +16,6 @@ module HM
   , TypedTerm(..)
     -- * Type inference
   , algW
-  , runTI
   ) where
 
 import Control.Monad.Except
@@ -92,13 +91,20 @@ unify (TypeFunction a b) (TypeFunction a' b') = do
 unify (Primitive a) (Primitive b) | a == b = return idSub
 unify a b = fail $ "cannot unify " ++ show a ++ " with " ++ show b
 
+tiLit :: Literal -> TI (Substitution, Type)
+tiLit (LBool _) = return (idSub, Primitive "Bool")
+tiLit (LInt _) = return (idSub, Primitive "Integer")
+tiLit (LFunc If) = do
+  a <- newVar
+  return (idSub, Primitive "Bool" `TypeFunction` (a `TypeFunction` (a `TypeFunction` a)))
+
 ti :: TypeEnv -> TypedTerm -> TI (Substitution, Type)
---ti _ (TTerm (Var v) (TScheme t@(Primitive _))) = return (idSub, t)
 ti e (TTerm tr sch) = do
   (s, t) <- ti e (NTTerm tr)
   sch' <- instantiate sch
   s' <- unify t sch'
   return (s', substituteT s' sch')
+ti _ (NTTerm (Lit l)) = tiLit l
 ti e (NTTerm (Var v)) = case Map.lookup v e of
   Nothing -> fail $ "unbound variable: " ++ v
   Just sigma -> do
@@ -123,7 +129,7 @@ ti e (NTTerm (Let x a b)) = do
   return (s1 `composeSub` s2, t2)
   
  
-algW :: TypedTerm -> TI Type
-algW t = do
+algW :: TypedTerm -> Either String Type
+algW t = fst . runTI $ do
   (s, u) <- ti Map.empty t
   return $ substituteT s u