Bruno Le Floch

I agree it would make sense to provide `\str_if_integer:nTF`, but it is not yet clear what the allowed integers should be. Presumably spaces should be allowed between signs, but not...

More generally it would be useful to have a command defined as `\ifvmode \if@noskipsec \leavevmode \global @noskipsecfalse \fi \if@inlabel \leavevmode \global \@inlabelfalse \fi \fi` or similar, meant to "put here...

I don't like `use_sorted` very much, and would perhaps prefer `sort_use`, meaning "sort" then "use". We have a few other `verb_verb` commands, like `\box_use_drop:N`, or `\tl_set_rescan:Nnn`, or `\tl_(trim_spaces)_apply:nN` which roughly...

I think it could be worthwhile to have an enum type, not to save \count registers but because it avoids setting the counter to a value that is beyond the...

Another motivation is that enums cannot be compared to integers (this can be achieved for us by storing enums in a way different from integers, e.g., simply as strings?)

Relatedly we could try using catcode tables (cctab) for `\ExplSyntaxOn`, with special handling to preserve the catcode of `@` (at least) to deal with the fact that people have been...

This is the usual problem with \\ followed by non-expandable material at the end of a table. The issue here is that \__file_input:n calls the non-expandable \__file_input_pop: after reading the...

Regarding the use of `\tl_set_eq:NN` or other, @car222222 opened an issue #791 and there is also some interesting discussion there.

Subtleties that could be worth documenting: - treatment of spaces (e.g., gotcha in ExplSyntax, `\~~a` is equivalent to `\~a`) - what tokens can be (meaning, catcode) - syntax of integer...

I did a tiny bit. Won't have time for more now but maybe we can be motivated to add to the file once in a while.