Re: [Haskell-cafe] Automatically generate sum type members -> [String]

19 May 2015

      On Tue, May 19, 2015 at 2:20 AM, Cody Goodman
 wrote:
...
data Codes = A0100A | A0500A deriving Show
codeExists "A0100A" = True
codeExists "A0500A" = True
codeExists _ = False
data Codes = A0100A | A0500A deriving Read

codeExists code =
  case reads code of
    [(_, "")] -> True
    _ -> False

Or with -XPatternGuards:

codeExists code | [(_, "")] <- reads code = True
                | otherwise = False

Re: [Haskell-cafe] Automatically generate sum type members -> [String]

Anatoly Zaretsky