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Int32.TryParse FSharp Implementation in Haskell

I liked the Int32.TryParse function in F # and wanted to make my own in Haskell:

import qualified Control.Exception as CE
handler:: CE.ErrorCall -> IO (Bool,Int)
handler e = return (False,0)
s2Int :: String->Int
s2Int s = read s
tryParse :: String -> IO (Bool,Int)
tryParse s = CE.catch (s2Int s `seq` return (True,read s)) handler

Seven lines to parse Int ?! Is there a shorter way?

Thank...

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2 answers


You can use reads

:

tryParse :: String -> (Bool, Int)
tryParse s =
    case reads s of
        [(i, "")] -> (True, i)
        _ -> (False, 0)


it would be more idomatic to return a Maybe Int

instead:

tryParse :: String -> Maybe Int
tryParse s =
    case reads s of
        [(i, "")] -> Just i
        _ -> Nothing
+9


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You can use readMaybe

from Text.Read

and get instead Maybe Int

:



import Text.Read

tryParse :: String -> Maybe Int
tryParse = readMaybe
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