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  1. mapEithers :: (a -> Either b c) -> [a] -> Either b [c]
  2. mapEithers f (x:xs) = case mapEithers f xs of
  3.                         Left err -> Left err
  4.                         Right ys -> case f x of
  5.                                       Left err -> Left err
  6.                                       Right y -> Right (y:ys)
  7. mapEithers _ _ = Right []
  8.  
  9. main = print $ (mapEithers Right "foo" :: Either () String)
Success #stdin #stdout 0s 6276KB
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Standard input is empty
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Right "foo"
https://ideone.com/gWIHlG
language:
Haskell (ghc 8.4.4)
created:
10 years ago
visibility:
public

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