Proposal: Functor and friends for the wrappers in Data.Monoid

Joachim Breitner mail at
Sat Feb 21 19:44:10 UTC 2015


Am Samstag, den 21.02.2015, 20:51 +0200 schrieb Oleg Grenrus:
> As Sean pointed out there is already a thread about this issue.
> I agree with Erik’s opinion, :
> > I'm +1 on the obviously useful instances (Data, Functor) and wouldn’t mind the others either, since I don't see any downsides.
> Simple use case for Functor is e.g. fromIntegral <$> s

I have no doubts about Data, Functor, Foldable and Traversable. Data
types like "Sum" have a clear container-like behavior.

It’s Applicative and Monad that I’m unsure about.

Joachim “nomeata” Breitner
  mail at joachim-breitner.de
  Jabber: nomeata at  • GPG-Key: 0xF0FBF51F
  Debian Developer: nomeata at

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