[:c2, :a3].sort returns [:a3, :c2] (high to low because of alphanumeric order. this is not what I would expect)
[:c2.to_i, :a3.to_i].sort returns [36, 57] (low to high because of numeric order. this seems right)
Is this intentional? I would expect notes to be sorted by frequency regardless of how they are specified.
Unfortunately this is intentional as :c2 is not a note, it’s a description of a note and given that Sonic Pi is built on top of a standard programming language (Ruby) it is sorted alphanumerically as you have observed.
I think the solution for this will be to introduce a new ring generator notes that converts all values within it to a MIDI number, then the following would work: