[Haskell-cafe] Void is not Monoid?

Javran Cheng javran.c at gmail.com
Sun Jan 13 07:59:36 UTC 2019

Hi Cafe,

I'm wondering why Data.Void does not have a Monoid instance, or, what would
be the problem if we do "mempty = absurd mempty"?

Long story: I was using a monad with some transformers, then I realize I
can collapse State and Reader into RWST with Void being Writer output.
(well, I could have just used Unit but I wanna give Void a try...) I know
beforehand that Void is Semigroup but is a bit surprise it doesn't have
Monoid instance.

Javran Cheng
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