[Haskell-cafe] Problem on overlapping instances

[Jasper Van der Jeugt]

Hello,

    {-# LANGUAGE OverlappingInstances, FlexibleInstances #-}
    import Data.Binary

    instance Binary [String] where
        get = undefined
        put = undefined

works fine here on GHC 6.12.3. That being said, it would be safer
perhaps to add a newtype around [String] so you can avoid the orphan
instance as well, i.e.

    import Data.Binary

    newtype MyType = MyType [String]

    instance Binary MyType where
        get = undefined
        put = undefined

Cheers,
Jasper

On Wed, Jan 5, 2011 at 9:24 AM, Magicloud Magiclouds
<magicloud.magiclouds at 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
>
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