DavidA wrote: > > newtype Lex = Lex Monomial deriving (Eq) > newtype Glex = Glex Monomial deriving (Eq) > > Now, what I'd like to do is have Lex and Glex, and any further monomial > orderings I define later, automatically derive Show and Num instances from > Monomial (because it seems like boilerplate to have to define Show and Num > instances by hand).
Good news: it's already implemented and called newtype deriving :) http://www.haskell.org/ghc/docs/latest/html/users_guide/type-extensions.html#newtype-deriving In short, you just write newtype Lex = Lex Monomial deriving (Eq, Show, Num) I guess that the Show instance will add the constructor Lex , though. Regards, apfelmus _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
