A *(foo, bar) B was deprecated

[rayegun]

The paper Novel Algebras for Advanced Analytics in Julia makes use of the syntax A *(foo, bar) B. It looks like this was deprecated at some point.

Is it possible for this syntax to make a return?

[mbauman]

I don't believe this ever worked; the Julia syntax in that paper is *(foo, bar)(A, B) (nb distinct from LaTeX math). General infix syntax for A f B is #16985; supporting A f() B is a further case of that issue.

[rayegun]

@mbauman @ViralBShah disagrees, that the capability existed at some point. The paper http://math.mit.edu/~edelman/publications/novel_algebras.pdf explicitly references the capability. I am aware of the previous issue, but I have my doubts about any of the proposals there being implemented in the near future given the lack of discussion since 2016. I'll look further into that issue. Hopefully there's a workable proposal there.

[ViralBShah]

There was a funny infix version that did work back then, but this was all pre 1.0.

[ViralBShah]

You had to do A *(max,+)B IIRC, and looking at the paper. The missing space was the key back then.

[rayegun]

Ah the space. It parses to multiplication by juxtaposition now or something to that effect if you don't have the second space.

[mbauman]

Even in Julia 0.1.2 (Mar 7, 2013) this parsed the way it does today:

julia> VERSION
v"0.1.2+113667293.r7252"

julia> :(A *(max,+)B)
:(*(A,*((max,+),B)))

julia> :(A *(max,+) B)
ERROR: syntax: missing separator in tuple

This predates me, and yes, I now see it in that figure caption, but I'd still be surprised if this ever worked (without some hacky *(::Tuple{Function, Function}, ::Matrix) lazy thing).

[ViralBShah]

I distinctly remember Alan showing that it worked. There were no other hacks. I am now curious and will try to dig this up.

[ViralBShah]

In any case, just to be clear, this is only of historical interest. I am not proposing reopening the issue.