2015-09-19から1日間の記事一覧
Eitherという型がありますが、eitherという関数もあります。 Either型 Data.Either Prelude> :i Either data Either a b = Left a | Right b -- Defined in `Data.Either' instance (Eq a, Eq b) => Eq (Either a b) -- Defined in `Data.Either' instance M…
import System.Environment (getArgs) import Control.Exception (catch, SomeException) main :: IO () main = do args <- getArgs out <- catch (readFile $ head args ) (\_ -> return "error") print out test$ runghc test02.hs test02.hs1 test02.hs:1…
getArgsを使う import System.Environment (getArgs) main :: IO () main = do args <- getArgs print args test$ runghc test02.hs [] test$ runghc test02.hs a ["a"] test$ runghc test02.hs a b ["a","b"] test$ runghc test02.hs ab ["ab"] test$ rungh…