RosettaCodeData/Task/Determine-if-a-string-is-numeric/Haskell/determine-if-a-string-is-numeric-1.hs

isInteger s = case reads s :: [(Integer, String)] of
  [(_, "")] -> True
  _         -> False

isDouble s = case reads s :: [(Double, String)] of
  [(_, "")] -> True
  _         -> False

isNumeric :: String -> Bool
isNumeric s = isInteger s || isDouble s