On 02/18/11 18:21, Edward Kmett wrote:

Hrmm, the strict version will violate the laws for Functor:

(fmap (const 12) . fmap error) /= fmap (const 12 . error)

That's an issue, though.  It means you can't use a Map that tries to keep its values always strict if you want to use class Functor with it.  *Even if* it's a separate type in Data.SomeMap.Strict. (Unless you're willing to break the law in the presence of _|_ values.)