This is exactly why I prefer Monoid over Semigroup. Having a law-abiding identity eliminates all sorts of corner caseshttps://twitter.com/carnivorous8008/status/871924374567231488 …
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Seems to me that preference shouldn't enter into it. Either that extra state should be representable, or not.
^ This person agrees. Why can't I use do-notation on (Writer (NonEmptyList x)) in Haskell ? I can even with Scala, and that's Scala!
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This is analogous to arguing "Why can't I use goto?" Sometimes forbidding functionality improves the code
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I'm not using that argument. There is no code that improves by the non-existence of Semigroup (or Monoid or any other appropriate thing).
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hmm, it would be neat to statically verify that you actually *use* a constraint, but `runWriter (pure ())` seems to forbid a `NonEmpty`
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Recent GHC versions warn of unnecessary constraints.
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