completing for release

1 files changed, 15 insertions, 0 deletions

diff --git a/examples/gfcc/compiler/ErrM.hs b/examples/gfcc/compiler/ErrM.hs
new file mode 100644
index 000000000..85c311a88
--- /dev/null
+++ b/examples/gfcc/compiler/ErrM.hs
@@ -0,0 +1,15 @@
+-- BNF Converter: Error Monad
+-- Copyright (C) 2004  Author:  Aarne Ranta
+
+-- This file comes with NO WARRANTY and may be used FOR ANY PURPOSE.
+module ErrM where
+
+-- the Error monad: like Maybe type with error msgs
+
+data Err a = Ok a | Bad String
+  deriving (Read, Show, Eq)
+
+instance Monad Err where
+  return      = Ok
+  Ok a  >>= f = f a
+  Bad s >>= f = Bad s