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  1. ifM :: Monad m => m Bool -> m a -> m a -> m a
  2. ifM act t e = do
  3.   b <- act
  4.   if b then t else e
  5.  
  6. anAction    = return False
  7. otherAction = return True
  8.  
  9. infixl 4 <?>
  10.  
  11. (<?>) :: Monad m => m Bool -> m a -> m a -> m a
  12. (<?>) = ifM
  13.  
  14. main :: IO String
  15. main =    anAction <?> do
  16. 			putStrLn "branch a"
  17. 			return "a"
  18. 		$ otherAction <?> do
  19. 			putStrLn "branch b"
  20. 			return "b"
  21. 		$ return "none"
Success #stdin #stdout 0s 4684KB
comments (?)
stdin 
Standard input is empty
stdout 
branch b
https://ideone.com/tBj6M3
language:
Haskell (ghc 8.4.4)
created:
10 years ago
visibility:
secret

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