Julia: Use of variable name for keyword argument key

[HarrisonGrodin]

Currently, keyword arguments must explicitly state the key and value being referenced in a call. However, this can be fairly verbose when both the value variable and kwarg key share the same name (e.g. f(; value = value)).

This issue proposes that f(; value) be interpreted as f(; value = value). A precedent for this style comes from ES6, namely { value } as the shorthand for { value: value }.

color = :green
printstyled("test"; color = color)  # current
printstyled("test", color)          # proposed

This is especially helpful for functions which recursively propagate keyword arguments:

f(x; kwarg) = x ≤ 0 ? kwarg : ("(" * f(x-1; kwarg = kwarg) * " | " * f(x-2; kwarg = kwarg) * ")")
f(x; kwarg) = x ≤ 0 ? kwarg : ("(" * f(x-1; kwarg) * " | " * f(x-2; kwarg) * ")")

The existing convention for right-precedence would not be affected.

[JeffBezanson]

I believe @davidanthoff suggested this during the discussion on named tuples, and indeed it's already implemented in julia-syntax.scm and would just need to be un-commented :)

[pablosanjose]

If this were done it should be conditional on using semicolon to denote the start of keywords

printstyled("test"; color)

Otherwise this convenience could end up calling unintended methods. Or at least it would be quite ambiguous

[StefanKarpinski]

Closing since most of the discussion is on the dup.