either

LeftとRightの値を処理する関数を渡してEitherを取り除く

code:hs

either :: (e -> c) -> (a -> c) -> Either e a -> c

例

code:hs

import Data.Either

test = either (+ 1) (* 2)

main = do

print $ test (Left 4) -- 5

print $ test (Right 4) -- 8