1 files changed, 26 insertions, 0 deletions
diff --git a/Utility/Conditional.hs b/Utility/Conditional.hs
new file mode 100644
index 000000000..85e39ec64
--- /dev/null
+++ b/Utility/Conditional.hs
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+{- monadic conditional operators
+ -
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Utility.Conditional where
+
+import Control.Monad (when, unless)
+
+whenM :: Monad m => m Bool -> m () -> m ()
+whenM c a = c >>= flip when a
+
+unlessM :: Monad m => m Bool -> m () -> m ()
+unlessM c a = c >>= flip unless a
+
+(>>?) :: Monad m => m Bool -> m () -> m ()
+(>>?) = whenM
+
+(>>!) :: Monad m => m Bool -> m () -> m ()
+(>>!) = unlessM
+
+-- low fixity allows eg, foo bar >>! error $ "failed " ++ meep
+infixr 0 >>?
+infixr 0 >>!