[FR] nothing-safe functions

[DhruvaSambrani]

This is a proposal to define

nothing_safe(f, def=nothing) = x -> isnothing(x) ? def : f(x)

This would help in a lot of places where intermediate functions return nothing, such as regex matches, findfirst etc

[KristofferC]

Isn't that pretty much just something(f(), def)?

[DhruvaSambrani]

If I understand correctly, something will evaluate f() and then return def if the result of f is nothing. Here, I'd want to operate f on something that is possibly nothing

[oxinabox]

Semantically, this is the behavior that is considered desirable for missing (propagation),
and not desirable for nothing (should be solved when occurs, either by solving, erroring or changing to missing if context implies this (common for parsing))

[vtjnash]

Isn't that pretty much just ?

@something(f(), def) FTFY

This definition (for nothing_safe) is possibly also frequently known as lift, and is something we've discussed adding: #36628

[DhruvaSambrani]

Close in favour of #36628