Generators as "Array Initializers"

[uniment]

(Related Discourse discussion)

This would be nice:

y = Array{Float64}(i+j for i=1:m, j=1:n)
y == Float64[i+j for i=1:m, j=1:n] # true

Would passing generators to the Array constructor be redundant with comprehensions? Yes. Why request it then? Because a) it'd create consistency with the fact that other similar constructors also accept generators (e.g. Tuple, NamedTuple, Dict, etc.), and b) it creates an idiom for non-standard arrays to be constructed with generators.

[rfourquet]

I would hope to not limit this feature to only generators, but any iterators. It would also provide an idiomatic solution to #47777: Vector{Float64}(rand(2, 2)), or Vector(rand(2, 2)), is probably the most straigthforward way to say "give me a vector out of this matrix".

[uniment]

any iterators

This seems like a disjoint feature, but maybe not a bad idea? Can you open a separate issue for it?

[vtjnash]

Yes, this is redundant with the definition of collect also, and also that yes we should finally implement this, as we already did for other constructors as you noted

[nsajko]

dup of #16029