Maduser:

I have started to program in Haskell. Now I want programm something like flags. It's a set of flags. It sould be possible to convert the Flag as Int/String (the bit combination). I have written this:

import Data.Set as Set

type Flags = Set Flag data Flag = Flag1 | Flag2 | Flag3 deriving(Eq, Ord, Enum, Show)

flagToInt :: Flags -> Int flagToInt flags = flag1 + flag2 + flag3 where flag1 = if member Flag1 flags then 1 else 0 flag2 = if member Flag2 flags then 2 else 0 flag3 = if member Flag3 flags then 4 else 0

but this seems to me to be inelegant. Can somebody help me making it better, please.

Something like: type Flags = [Flag] data Flag = Flag1 | Flag2 | Flag3 deriving (Eq, Ord, Enum, Show) flagToInt :: Flags -> Int flagToInt = sum . map ((2 ^) . fromEnum) Perhaps? -- Don