Aesthetic changes: add (!?) and (!?>) operators + some docs.

joelwilliamson / bimap

Bidirectional mapping between two key types

BSD 3-Clause "New" or "Revised" License

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Aesthetic changes: add (!?) and (!?>) operators + some docs. #15

Closed bingis-khan closed 2 years ago

bingis-khan commented 2 years ago

As the title suggests:

Two new operators (!?) and (!?>) which correspond to flip lookup and flip lookupR.
Really minimal documentation for those two.
lookup note that mentions how this lookup compares to the Data.Map's lookup function.

The last one is important, I think, because it wasn't immediately obvious (for me :) ) that MonadThrow includes Maybe and lookup works the same way as Data.Map's lookup if m is Maybe. Added this bit in the docs "for educational purposes", basically.

Again, really small change, but I think it'd make the library just this much nicer.

bingis-khan commented 2 years ago

As a side note, I originally forked this repository, because I was surprised that it has no Semigroup/Monoid instance. After looking into it, I'm pretty sure a non-trivial Semigroup instance is basically impossible.

joelwilliamson commented 2 years ago

I'm fine with this change in principle. Some comments:

!? and !?> appear to be lookup(R), not flip lookup(R). Was this intentional or did you miss the flip?
A quick look at hackage didn't show !? and !?> operators in containers:Data.Map. Can you link me to their documentation so I can verify these have similar semantics?

Thanks for the PR.

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As a side note, I originally forked this repository, because I was surprised that it has no Semigroup/Monoid instance. After looking into it, I'm pretty sure a non-trivial semigroup instance is basically impossible.

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bingis-khan commented 2 years ago

Oh no. I've accidentally removed the flip change while I was fiddling with git rebase. Yeah, it's totally not intentional! The (!?) link: https://hackage.haskell.org/package/containers-0.6.5.1/docs/Data-Map-Strict.html#v:-33--63-