Reserved words in julia-parser.scm

[bkamins]

There seem to be the following reserved words missing in julia-parser.scm:

• mutable, abstract, primitive in initial-reserved-keywords;
• elseif, type, where in reserved-words.

Maybe it is intentional and I am not sure how relevant this is and if I have classified them correctly.

However, the source says in todo comment that the list should be completed so I am reporting this.

[JeffBezanson]

mutable, abstract, and primitive are not reserved; they're only special when followed by type or struct. type is also not reserved for the same reason. where is resolved contextually and so it's also not really reserved; it can be used as a variable name.

I think elseif could be added to the list without changing any parsing.

[bkamins]

Thanks for explanation. The only ambiguity I would guess it introduces is:

julia> primitive = 10
10

julia> type = 100
100

julia> [primitive type]
ERROR: syntax: unexpected "]"

but it is handled correctly.

I will add elseif to reserved-words to check if anything fails and I guess @JeffBezanson can decide if it is worth to merge it.

[bkamins]

@mbauman Regarding your doc tag in #29222:

I think it would be good to document what @JeffBezanson put down in this issue as it is not obvious but I am not sure what would be the best place for it (probably somewhere around https://docs.julialang.org/en/latest/base/base/#Keywords-1).

[mbauman]

The brief intermittent doc tag was just a bad prior on my part: I assumed the change must be documentation because surely elseif is already reserved in the parser. The next step in my review was actually looking at the code… :)

Yeah, it seems like that Keywords section could use just a brief introduction about what those words all are.

[bkamins]

OK - I will try to add an appropriate section as I have seen this question popping up.

[JeffBezanson]

Just to clarify, it's worth noting that the parser doesn't actually need a list of all the "reserved" words in one place, since they don't all have the same parsing. We also need to distinguish words that are fully reserved and can't be used as variable names, from those that are mostly free to use but have some special syntax associated with them.

[bkamins]

Understood (hopefully 😄). I have tried to capture documentation of this distinction in #29229.