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 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe