this post was submitted on 27 Mar 2024
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Functional Programming

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[–] [email protected] 12 points 5 months ago (3 children)

I've submitted this link because the topic is interesting to me, and [email protected] is practically dead, with the last post dating back over 10 days.

For those who are down voting the contribution, be my guest and do better: submit interesting content.

[–] [email protected] 8 points 5 months ago (1 children)

Lemmy has a few perpetually online perpetual assholes that down vote anything they see - give a post a few hours and you'll see the reasonable people show up.

[–] [email protected] 3 points 5 months ago* (last edited 5 months ago) (1 children)

Honestly, I don't mind the downvotes. What puzzles me is how some people feel strongly enough about a topic to subscribe to a community, but still feel compelled to slap down contributions in a time nothing is being submitted, as if seeing no new posts is better than seeing a post that might not tickle their fancy.

It's the difference between building up and tearing down.

[–] [email protected] 1 points 5 months ago

FWIW due to Lemmy’s size, I think it’s actually more common to scroll Local or All rather than Subscriptions, so you’re probably getting votes from lots of random people rather than subscribers to this community specifically.

[–] [email protected] 4 points 5 months ago

Have an upvote. Thanks for trying. Interesting to me also, but yeah, its dead in here.

[–] [email protected] 12 points 5 months ago (1 children)

On the latest Haskell interlude podcast, the guest was talking about how using the ReaderT monad specifically introduces safety issues. My ears perked up because I’m right in the middle of leaning on it heavily in one of my Haskell projects.

[–] [email protected] 3 points 5 months ago (1 children)

@demesisx @lysdexic No safety issues mentioned around ReaderT. The speaker was talking about how stacking monad transformers mtl-style can generate unnecessary closures that GHC can't optimise away.

[–] [email protected] 11 points 5 months ago

Thanks for the clarification.

[–] [email protected] 4 points 5 months ago

A monad is just a monoid in the category of endofunctors, what's the problem?

[–] [email protected] 1 points 5 months ago

I've recently come to appreciate monads as 2-arrows from the terminal object in a 2-category; quoting nLab:

… a monad in [a category] K is a lax 2-functor from the terminal bicategory 1 to K: the unique object * of 1 is sent to the object a, the morphism 1 becomes [the endomorphism] t, and [the unit] η and [the join] μ arise from the coherent 2-cells expressing lax functoriality.

This is a nifty demystification of the data of a monad. Why do endofunctors tend to carry monads? Because endofunctors on categories C tend to be expressible as endomorphisms in 2-categories where C is an object! Since this latter condition is typically trivial, it follows that endofunctors on C typically carry monads (and that any counterexamples depend on the structure of C and choice of 2-category.)