filter.comap₂

Stream: Is there code for X?

[Yaël Dillies]

Just as we have docs#set.image2, should we have filter.comap₂? I'm staring at docs#filter.has_mul to see whether we can abstract something away.

[Yaël Dillies]

The answer seems to be that we should have more filter constructors using docs#inf_top_hom.

[Yury G. Kudryashov]

It should be called filter.map₂, not filter.comap₂, because it is (f₁.prod f₂).map (uncurry (*))

[Yury G. Kudryashov]

(not tested)