added Functor instance for Err datatype

2003-10-06 08:37:59 +00:00
parent 0ac49ec12f
commit 7aa7a3cf19
1 changed files with 4 additions and 0 deletions
--- a/src/GF/Data/Operations.hs
+++ b/src/GF/Data/Operations.hs
@@ -26,6 +26,10 @@ instance Monad Err where
  Ok a  >>= f = f a
  Bad s >>= f = Bad s

+instance Functor Err where   -- added 2/10/2003 by PEB
+  fmap f (Ok a) = Ok (f a)
+  fmap f (Bad s) = Bad s
+
 -- analogue of maybe
 err :: (String -> b) -> (a -> b) -> Err a -> b 
 err d f e = case e of