1 files changed, 37 insertions, 0 deletions
diff --git a/compiler/ilxGen/tests/test19.hs b/compiler/ilxGen/tests/test19.hs
new file mode 100644
index 0000000000..a292599031
--- /dev/null
+++ b/compiler/ilxGen/tests/test19.hs
@@ -0,0 +1,37 @@
+
+{-# OPTIONS -fno-implicit-prelude -#include "cbits/stgio.h" #-}
+
+
+module Test19 where
+
+import PrelST
+import PrelBase
+import PrelErr
+
+newtype IIO a = IIO (State# RealWorld -> (# State# RealWorld, a #))
+
+unIIO :: IIO a -> (State# RealWorld -> (# State# RealWorld, a #))
+unIIO (IIO a) = a
+
+instance  Functor IIO where
+   fmap f x = x >>= (return . f)
+
+instance  Monad IIO  where
+    {-# INLINE return #-}
+    {-# INLINE (>>)   #-}
+    {-# INLINE (>>=)  #-}
+    m >> k      =  m >>= \ _ -> k
+    return x	= returnIIO x
+
+    m >>= k     = bindIIO m k
+    fail s	= error s -- not ioError?
+
+
+bindIIO :: IIO a -> (a -> IIO b) -> IIO b
+bindIIO (IIO m) k = IIO ( \ s ->
+  case m s of 
+    (# new_s, a #) -> unIIO (k a) new_s
+  )
+
+returnIIO :: a -> IIO a
+returnIIO x = IIO (\ s -> (# s, x #))