This is a great idea! But 'a' may not always be a char-like thing. Maybe chunk is a better name? We could make instances for other string-like types, giving the recommended way to concat a list of string-like things.
class IsStringChunk a where
fromChunkList :: [a] -> String
instance IsStringChunk Char where
fromChunkList = id
instance IsStringChunk a => IsString [a] where
fromString = fromChunkList
Sjoerd
On Aug 25, 2013, at 11:48 AM, Henning Thielemann
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
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