Am Donnerstag 17 September 2009 15:56:03 schrieb José Pedro Magalhães: > Hey Andy, > > On Thu, Sep 17, 2009 at 15:40, Andy Gimblett <hask...@gimbo.org.uk> wrote: > > Now, some of those algebraic data type types happen to be > > enumerations; in this case, my idea is to list the constructors, with > > the rule that each constructor's position in the list is the Int which > > gets converted into that constructor. > > > > > class Enumerated a where > > > constructors :: [a] > > > > E.g. here's a type Bar with three constructors: > > > data Bar = X | Y | Z deriving (Show) > > > instance Enumerated Bar where > > > constructors = [X, Y, Z] > > > > (This is certainly ugly. Any suggestions?) > > > |constructors| is expressible in SYB: Wow.
What about data Bar = X | Y | Z deriving (Show, Eq, Ord, Enum, Bounded) instance Enumerated Bar where constructors = [minBound .. maxBound] ? _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe