TIL: loop variables can be an element of an array, dict, etc

General Usage
1

Been using Julia for several years and only just realised that you can use elements of an array, dict, etc as a loop variable. Eg

julia> v = zeros(Int, 3); for v[1] ∈ 0:3, v[2] ∈ v[1]:3, v[3] ∈ v[2]:3
         println(v)
       end
[0, 0, 0]
[0, 0, 1]
[0, 0, 2]
[0, 0, 3]
[0, 1, 1]
[0, 1, 2]
[0, 1, 3]
[0, 2, 2]
[0, 2, 3]
[0, 3, 3]
[1, 1, 1]
[1, 1, 2]
[1, 1, 3]
[1, 2, 2]
[1, 2, 3]
[1, 3, 3]
[2, 2, 2]
[2, 2, 3]
[2, 3, 3]
[3, 3, 3]

Not a big deal but kinda neat

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2

Also works for properties (dots, setproperty! shows up in Meta.@lower). This isn’t documented so I’m tentatively considering this an unstable lowering quirk.

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