operator overloading

[felixroos]

One possible feature that we haven't really explored is operator overloading. It's also a decision of how much "strangeness", we let into strudel syntax, aka language strangeness budget, as @yaxu pointed out. It is generally possible to overload operators as part of the eval package, so the questions are:

• Should we even add overloaded operators?
• If yes, which ones? see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators for a list of candidates
• Compatibility with tidal cannot really be met, maybe some common operators with haskell (if any) and python / vortex (at least >>>) can be found

[yaxu]

I think having some overloaded operators is inevitable. Just methods would work, but in a way a method is an overloading of the . operator, and I think only having that one operator is a bit too limiting. However, anything achievable with an overloaded operator will/should probably also be achievable with/be shorthand for a class method.

I think basic arithmetic like + - * / % ** should keep its meaning and just be lifted into operating pattern values, where structure ('whole' timespans in event fragments) is preserved from the left. We currently have add, sub, mul and div methods for this, which should probably be renamed to something like addLeft etc, with addRight and addBoth etc for versions that preserve structure from left, right and both sides. I'm not sure if the bare add should then be an alias for addLeft like +, or addBoth.

Arrow-like operators < > <= >= <<= >>= and >>> have high value in e.g. manipulating time/chaining things together and should be spent wisely :) Likewise & | ^ && || ??.

Could we potentially overload in?

[felixroos]

related: #82 #96