JuliaLang/julia — comment on commit a6dc8c5470d4a9e3bef42f5a116a4241d0db6fa0
File: j/set.j line 45
By JeffBezanson:

Eh, I don't know about this, it seems too fancy. How important is it to union sets with different element types? And it doesn't seem to buy much performance, since type inference can't figure out this loop, and unioning Set{Int32} and Set{Int64} gives Set{Any}, for example.