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[project @ 1999-05-18 15:03:54 by simonpj]
[ghc-hetmet.git]
/
ghc
/
compiler
/
utils
/
Maybes.lhs
diff --git
a/ghc/compiler/utils/Maybes.lhs
b/ghc/compiler/utils/Maybes.lhs
index
98efdb7
..
2f6118f
100644
(file)
--- a/
ghc/compiler/utils/Maybes.lhs
+++ b/
ghc/compiler/utils/Maybes.lhs
@@
-8,6
+8,7
@@
module Maybes (
-- Maybe(..), -- no, it's in 1.3
MaybeErr(..),
-- Maybe(..), -- no, it's in 1.3
MaybeErr(..),
+ orElse,
mapMaybe,
allMaybes,
firstJust,
mapMaybe,
allMaybes,
firstJust,
@@
-29,6
+30,9
@@
module Maybes (
#include "HsVersions.h"
import Maybe( catMaybes, mapMaybe )
#include "HsVersions.h"
import Maybe( catMaybes, mapMaybe )
+
+
+infixr 4 `orElse`
\end{code}
\end{code}
@@
-96,6
+100,10
@@
returnMaybe = Just
failMaybe :: Maybe a
failMaybe = Nothing
failMaybe :: Maybe a
failMaybe = Nothing
+
+orElse :: Maybe a -> a -> a
+(Just x) `orElse` y = x
+Nothing `orElse` y = y
\end{code}
Lookup functions
\end{code}
Lookup functions