Parser does not correspond to grammar for `concept` about nim

[metagn]

Could you please advise whether we need to change the grammar files

The comments in the parser.nim file starting with #| are turned into the grammar documentation file when executing the parser file as the main module, i.e. nim r compiler/parser.nim. So to change the wrong line in the grammar, one would change the comment in this line:

Nim/compiler/parser.nim

Line 2208 in 9648d97

#| conceptParam = ('var' | 'out')? symbol

to say ('var' | 'out' | 'ptr' | 'ref' | 'static' | 'type'), then run nim r compiler/parser.nim.

A separate issue exists where this line:

Nim/compiler/parser.nim

Line 2192 in 9648d97

of tkOut, tkVar: nkVarTy

needs to be split into of tkVar: nkVarTy and of tkOut: nkOutTy (nkOutTy is new).

[arnetheduck]

well, the grammar, parser and AST for concepts is .. experimental as a whole at best - its indentation rules generally deviate from the language, keywords such as type are used in an irregular way compared to the rest of the language etc.

I think there are deeper questions to resolve than this grammar quirk before venturing further.

[metagn]

Also the concept parameter out x seems to parse the same as var x (this line predates the new out type):

Nim/compiler/parser.nim

Line 2192 in 9648d97

of tkOut, tkVar: nkVarTy

[silly-carbon]

Hi @arnetheduck @metagn

I'd like to try to solve this issue. But as I can see from the codebase, other symbols other than var & out are also supported, e.g., ptr, ref, static, type.
But I can see from this link (https://nim-lang.org/docs/manual_experimental.html#concepts):

You can apply any of the standard type modifiers such as var, ref, ptr and static to denote a more specific type of instance

It seems that those symbols are supported as described in the doc listed above, just the grammar files need to be updated.

Could you please advise whether we need to change the grammar files (to add more symbols like ptr, ref, static, type. IMHO, this is more feasible),
or to change the codebase(to remove support of ptr, ref, static, type)?

[silly-carbon]

Thanks very much for your responses. Could you please share more suggestions on this?

…

________________________________ From: Jacek Sieka ***@***.***> Sent: Wednesday, January 24, 2024 6:31:40 PM To: nim-lang/Nim ***@***.***> Cc: Silly Carbon ***@***.***>; Comment ***@***.***> Subject: Re: [nim-lang/Nim] Parser does not correspond to grammar for `concept` (Issue #23085) well, the grammar, parser and AST for concepts is .. experimental as a whole at best - its indentation rules generally deviate from the language, keywords such as type are used in an irregular way compared to the rest of the language etc. I think there are deeper questions to resolve than this grammar quirk before venturing further. — Reply to this email directly, view it on GitHub<#23085 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AKS4ZZFMSEVHT6K2F6DW72TYQDPIZAVCNFSM6AAAAABAXNC7WOVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSMBXHA2DSNRVHE>. You are receiving this because you commented.Message ID: ***@***.***>