By 'token' do you mean a note, a chord, general structure (verse, bridge, etc.), a well known phrase?
Music is so full of cliche I don't doubt that someone will write software (probably already has) to assist a composer, generate drum parts or harmony, etc.
I like the idea of a Rhythm changes generator. With enough monkeys the Flintstone Theme eventually pops out.
A token can be almost anything as long as a sequence of tokens represent something meaningful. For music, I and many others have represented music as sequences of notes interleaved with rests of varying length. E.g "A--3 R3 C#-2" Three tokens to be interpreted as "play an A note in the 3rd octave at tic 0, wait 3 tics, play a C# note in the 2nd octave at tic 4". As you can imagine, the number of tokens grow very fast especially for polyphonic music.
You might say that that level of detail is unnecessary for most music. For a 12-bar blues in E you might only need five tokens, "blues 12 bars key E", to represent the whole song. But what if you want to add some cool pentatonic riffs to it and maybe a key change in the middle? Either you add token types for "key change in the middle" and "cool pentatonic riffs" or you will need many more tokens to represent your song.
One can think of it as compression. English text is trivial to compress because you just match each word to a word index in a lookup table. Compositions are way harder to compress.
An important reason why it is so hard to compress them is that errors frequently don't really matter in the same way they do with language. You can really play a melody with many, many variations and it is still (to a point) the same melody. This is much harder to do with language, and has important implications when thinking about what a composition "actually is".
Music is so full of cliche I don't doubt that someone will write software (probably already has) to assist a composer, generate drum parts or harmony, etc.
I like the idea of a Rhythm changes generator. With enough monkeys the Flintstone Theme eventually pops out.