I wanted to ask why type promotion/widening doesn’t use more unions. For example (on 0.62): x=Any[Int32(0), 0]; typeof(collect(i for i in x)) Array{Signed,1} More specifically: Widening takes the most specific abstract supertype. The in-memory representation is, as far as I understand, not more ef…

[image] foobar_lv2: (realistically I would probably take a more conservative limit on union size, e.g. 16, and remove the special handling of Missing/Nothing unions) The compiler is not currently equipped to handle such unions well.

Type promotion: Why not use more unions?

Internals & Design

stevengj February 1, 2018, 8:23pm 2

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Type promotion: Why not use more unions?

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