Re: [Haskell-beginners] Randomly selecting a data constructor

Thomas Davie wrote:

data FigType = TR1 | TR2 | TR3 | TR4 | SQ | L1 | L2 | Z1 | Z2 | Z3 | Z4 | NoFigure                deriving (Enum) randomFigure :: IO FigType randomFigure = toEnum <$> randomRIO (1,11)

You actually want randomRIO (0,10). If you don't want to have to remember that, or to remember to change "10" whenever the number of constructors changes, you can use:

data FigType = TR1 | TR2 | TR3 | TR4 | SQ | L1 | L2 | Z1 | Z2 | Z3 | Z4 | NoFigure deriving (Enum, Bounded) randomFigure :: IO FigType randomFigure = toEnum <$> randomRIO (fromEnum (minBound :: FigType), fromEnum maxBound)

Regards, Yitz