Short syntax for connecting events

[wvengen]

RMididings currently uses Fork!, Chain! and Not! to connect events. The mididings syntax with //, >> and ~ is easier to read. With Rust's procedural macro's it may be possible to add mididings-native syntax. For example, the inline_python crate parses Python-code with a Rust procedural macro (development blog series). It would be great if people could copy and paste mididings patches into RMididings, or get close to that.

[wvengen]

Work started in branch proc-macro.

[wvengen]

At this moment, the work in progress is a patch! macro that accepts a syntax closer to mididings.

A > B - chain
A / B, [A, B] - fork
*A - add, i.e. [Pass(), A]
!A - invert, i.e. Not!(A)

Since we are using the Rust parser (and would like to keep using it), not all syntax is possible: // doesn't exist as an operator, so we resort to /. To keep things consistent > is used instead of >>. The tilde ~ is no operator in Rust, so we use !. The plus + is no unary operator, so we use *. We will be able to use - as unary operator for negation.