On Sun, Aug 25, 2013 at 5:48 AM, Henning Thielemann <schlepptop@henning-thielemann.de> wrote:

Am 24.08.2013 19:52, schrieb Edward Kmett:

I would like to replace this instance with

instance a ~ Char => IsString [a] where
   fromString = id

Your complaint proves my concerns about those FlexibleInstances. The best instance is a Haskell 98 instance:


class IsCharList a where
   fromCharList :: [a] -> String

instance IsCharList Char where
   fromCharList = id

instance IsCharList a => IsString [a] where
   fromString = fromCharList


This is both the most flexible solution and it is portable.

http://www.haskell.org/haskellwiki/List_instance