[project @ 1998-12-02 13:17:09 by simonm]

[ghc-hetmet.git] / ghc / interpreter / test / typechecker / t005.hs

diff --git a/ghc/interpreter/test/typechecker/t005.hs b/ghc/interpreter/test/typechecker/t005.hs
new file mode 100644 (file)
index 0000000..fd58627
--- /dev/null
+++ b/ghc/interpreter/test/typechecker/t005.hs
@@ -0,0 +1,21 @@
+--!!! Test for error in type error message (fixed in Hugs 1.4)
+module TyErr where
+
+newtype StateMonad m s a = MkStateMonad (s -> (m (s, a)))
+
+instance Monad m => Monad (StateMonad m s) where
+    (>>=) (MkStateMonad fn1) f
+       = MkStateMonad (\st -> (do res <- fn1 st
+                                  case res of
+                                      (st', res') -> extrStateMonad (f res') st'))
+    return val = MkStateMonad (\st -> (return (st, val)))
+                          
+extrStateMonad (MkStateMonad f) = f
+
+getState :: Monad m => StateMonad m s s
+getState = MkStateMonad (\st -> return (st, st))
+
+-- popIndentList :: StateMonad IO Int ()
+popIndentList = 
+    (do getState
+       return ())