By the way is there any reason you couldn't attach laws to just like, a record of functions? Why are classes special?
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You're on to something very fundamental about type classes ;-)
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What is it?
(Not sure if I should be thinking in the direction of "they're actually not special" or "they're more special than I think!")
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Type classes are just a fancy, built-in way of passing records of functions around implicitly. Alas, they live in a separate language space.
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I'm guessing you are already aware of this though 😉
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I mean nothing too profound -- type classes tie "laws" to type-directed implicit arguments in a way that mystifies the two distinct concepts
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in ML signatures specify an interface -- over both types and values -- and you can associate laws with the signature. much neater imo!
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Tbh part of me regrets not having a sufficiently-strong set of counterarguments ready at the time, against the push for traits in Rust.
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Tbh I do prefer the 'programming with interface constraints' feeling I get using TCs. I would prefer traditional TCs over ML modules…
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For something like Eq, I really want implicit module passing. Damnnit if I'm gonna pass around/instantiate that module manually.
yup punting for so long on solving this problem properly (see also Standard ML's "eqtype" nonsense) is a big failing of the ML community
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I think they've punted because the right answer is the kind of implicitness that ML people (such as ) dislike.
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