broadcast(== produces Vector{Real} and not Vector{Bool}

[mauro3]

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julia> (==).(Real[1],[2])
1-element Array{Real,1}:
 false

julia> Real[1].==[2]
1-element BitArray{1}:
 false

Shouldn't both return the same type? Preferably a BitArray.

[stevengj]

This is mostly a duplicate of #17623; the .== functions are not yet handled by broadcast. (That PR is currently stalled until broadcast functions with sparse arrays are improved; @Sacha0 is working on that.)

One difficulty with returning BitArray is that it doesn't work easily with fusion. e.g. in #17623 z .== y & y .> 0 will be fused into a single broadcast call, specialized broadcast methods for == etcetera are not called.

One option is to always return a BitArray from broadcast operations returning Bool. However, it's not clear to me that this is a good idea. Furthermore, given fusion, it seems that the advantage of bitarrays is greatly reduced: if you are producing multiple temporary arrays, a BitArray is much more attractive, combined with the fact that .& and .| operations for bitarrays can be faster than those operations on Bool arrays.

[mauro3]

Is this not also some promotion issue? It works with Number (well it return a Vector{Bool} but that is fine too):

julia> (==).(Real[1//2, 1//2], [1,2])
2-element Array{Real,1}:
 false
 false

julia> (==).(Number[1//2, 1//2], [1,2])
2-element Array{Bool,1}:
 false
 false

[stevengj]

@mauro3, ah right, I didn't notice the Vector{Real} type. That is a separate issue from whether to return BitArray. cc @pabloferz

[pabloferz]

The Vector{Real} issue should be fixed by #18642.

[stevengj]

I think this can be closed now: as of #17623, broadcast always returns a BitArray for functions returning Bool.

[tkelman]

should add tests for that, if there aren't any yet