You can't. If you have special semantics for [String], then it is not really a [String], it is something else. So let the type system know that:
newtype SomethingElse = SomethingElse [String] instance Binary SomethingElse where ... On Wed, Jan 5, 2011 at 1:24 AM, Magicloud Magiclouds <magicloud.magiclo...@gmail.com> wrote: > Hi, > I am using Data.Binary which defined "instance Binary a => Binary > [a]". Now I need to define "instance Binary [String]" to make > something special for string list. > How to make it work? I looked into the chapter of > overlappinginstances, nothing works. > -- > 竹密岂妨流水过 > 山高哪阻野云飞 > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe