string division: "pre"\"prefix" => "fix", "suffix"/"fix" => "suf".

[StefanKarpinski]

I realized that writing string concatenation as * allows you to naturally use \ to strip prefixes from strings and / to strip suffixes from them, which is kind of cute.

[JeffBezanson]

Is it April 1st already?

[StefanKarpinski]

Nope. This is mathematically sound. Try doing this with minus.

[toivoh]

Could be useful. Agree that it's consistent.

[JeffBezanson]

I also agree it's consistent, but I didn't think we wanted to double down on using arithmetic operators on strings.

[ScottPJones]

Also - why in Base, when these could perfectly well go into a package, for anybody who thinks they might be useful?

[carnaval]

mod(x::String,y::String) = replace(x, y, "") also ?

[GunnarFarneback]

This does seem like a rather marginal use to occupy an operator for. I'd prefer to have it undefined in Base so I can keep mapping / to split in my own code without warnings.

[StefanKarpinski]

We should either stop using * for string concatenation or we should "double down". The point of this PR is that it occurred to me that viewing string concatenation mathematically does suggest a consistent larger vocabulary. Whether we want to use that vocabulary or not is a different question. Take this PR as food for thought.

[StefanKarpinski]

I think the saner alternative here is probably to keep in mind that there's an algebraic structure to strings and regexes but not use arithmetic ops for it.

[pabloferz]

https://en.wikipedia.org/wiki/String_operations#Right_quotient

[StefanKarpinski]

Yes, this is not a totally made up operation – the notation even matches what's used in academic literature (which is why I chose * for string concatenation in the first place). I find it strange that the operation produces "" when the suffix/prefix doesn't match. I wonder what the rationale for that is.

[toivoh]

Yeah, that's strange. Seems that it would destroy a lot of useful properties that the operation would satisfy otherwise (in the cases when it is defined).