i keep trying to find something that feels terribly obvious but i can't make any link.

say i have a function of the following type:

is SomeClass supposed to be BiFunctor or something else?

clearly, what i want to do is to combine the elements of the first pair into the elements of the second, preferrably without pattern matching, that is, merely in function of (:).

i think the problem with bifunctor is that it seems to only allow the application of both arguments in a separate fashion. but here the first argument is in one block, that is (a,b).

i know, ofc we could do something like:

foo pair pairList = bimap (fst pair :) (snd pair:) pairList

or maybe use curry or whatever. but i'd like my pair to not need to be unboxed!

is there not a way to not have to manually call fst and snd? are both of these functions typeclass methods by any chance? then we could write a generalized function that could work for any f = (:) or any kind of pair-like thingy. mind you i'm not sure to which extent it would keep the opacity of the type constructor (,).

especially, it's a bit like unboxing the Maybe type constructor: you can do it manually by pattern matching, but when you have the exact same issue but with IO, it's not possible anymore to unbox the underlying type

equally, i bet one could invent IO a b, in a way that you could not just get a and b, but you could somehow implement