HI, Am Samstag, den 21.02.2015, 21:26 +0000 schrieb Oliver Charles:
Having Applicative might be nice for `pure`. That way we can getSum . foldMap pure, and so on. Of course, in that case using `Sum` is no different, but this opens up the ability to construct `Sum`s from other parts of code that simply require `Applicative`.
is that any better than "getSum . foldMap Sum"? Adding an Applicative instance, when the only main use case is to cover-over the lack of a Pointed type class, does not seem to be a good guiding principle. BTW, coerce would work as well here, if you for some reason want to use a polymorphic argument to foldMap. Still not convinced :-), Joachim -- Joachim “nomeata” Breitner mail@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata@joachim-breitner.de • GPG-Key: 0xF0FBF51F Debian Developer: nomeata@debian.org