Bowtie symbol isn't a valid character.

[rofinn]

julia> ⋈ = 1
ERROR: syntax: invalid character "⋈"

FWIW, \bowtie tab completed on the REPL.

[JeffBezanson]

Ah, one of those category Sm characters. They have a range of meanings so we need to whitelist them. Should this be an operator or just an identifier character?

[stevengj]

Yes, ⋈ (U+22c8) was one of the characters that got left out because it wasn't immediately clear if it should be an operator or an identifier.

It seems like it is mainly used as a relation symbol. Most of these relational algebra symbols were added in #8036. Confusingly, the join symbol ⨝ (U+2a1d) (tab-complete \Join) is already supported as an infix operator, and looks nearly identical to the "bowtie".

One option would be to add a mapping to our custom Julia Unicode normalization that simply parses ⋈ (U+22c8) as equivalent to ⨝ (U+2a1d).

[rofinn]

I would like to use it as an infix operator for natural join between 2 relations, but I'd be fine if it was just a valid function name.

[rofinn]

Oh, I didn't realize they were different unicode symbols. I'm fine using the join symbol, but \join wasn't tab completing on the REPL in 0.6 or 0.7 (5 days old).

[StefanKarpinski]

It's capital \Join not \join (I have no idea why).

[StefanKarpinski]

Normalizing these seems sane since they like exactly alike.

[stevengj]

The reason it was \Join is because it is that way in LaTeX, and we were hesitant about innovating in LaTeX names in #8036. I agree that adding the lower-case tab completion, along with the normalization, makes sense.

[stevengj]

One oddity is that \Join seems to be treated as a fullwidth character, while bowtie is treated as narrow:

julia> charwidth('⋈') # bowtie
1

julia> charwidth('⨝') # join
2

(\Join displays oddly in the REPL too, similar to #3721, since my (Mac) terminal also seems to be confused about its character width.)

[JeffBezanson]

My terminal and/or font seems to have the widths swapped --- bowtie takes up 2 columns (though the terminal doesn't know it) and join takes up 1.

[iamed2]

My terminal handles \Join correctly but Julia doesn't

EDIT: Julia with OhMyREPL displays it with one column but moves the cursor symbol another column right, despite typing in the correct place. Julia without OMR displays it with 2 columns but removes second column on backspace.

EDIT 2: I have iterm2 with Unicode 9 widths turned on; that's probably relevant

[rofinn]

Would there be any issue with making all the unicode substitutions case-insensitive? Is there an example where the casing would matter?

[stevengj]

@rofinn, since the same tab-substitution list is now supported by several editors, and we can't control the case sensitivity of editor tab substitution without providing an explicit list of all possibilities (\Join, \JOiN, …), I think it's better for consistency's sake to just a support a limited set of variations. (e.g. \Join and \join).

See also the discussion in #21646 about rationalizing the latex completions.

[StefanKarpinski]

IIRC, there are examples where case matters in LaTeX escapes.

[iamed2]

Example:

\delta: δ
\Delta: Δ

[rofinn]

Alright, I forgot about \delta vs \Delta.

[stevengj]

Update: \join and \Join nowadays both tab-complete to U+2A1D. It's still not clear what to do about \bowtie (U+22C8).