[project @ 2001-01-17 15:23:39 by sewardj]

[ghc-hetmet.git] / ghc / interpreter / test / typechecker / t012.hs

diff --git a/ghc/interpreter/test/typechecker/t012.hs b/ghc/interpreter/test/typechecker/t012.hs
deleted file mode 100644 (file)
index 391bff0..0000000
--- a/ghc/interpreter/test/typechecker/t012.hs
+++ /dev/null
@@ -1,22 +0,0 @@
---!!! runST (the classic rank 2 type example)
-
-newtype ST s a = MkST (s -> (a,s))
-
-unST :: ST s a -> (s -> (a,s))
-unST (MkST f) = f
-
-runST :: (forall s. ST s a) -> a
-runST m = case unST m () of { (a,_)  -> 
-          a
-         }
-
-returnST :: a -> ST s a
-returnST a = MkST (\s -> (a,s))
-
-thenST :: ST s a -> (a -> ST s b) -> ST s b
-thenST m k = MkST (\ s0 -> case unST m s0 of { (a,s1) -> unST (k a) s1 })
-
-instance Monad (ST s) where
-    return = returnST
-    (>>=)  = thenST
-