The Lily# language

How to read this

This is a reference to the .lys language as Lily# 0.16.0 accepts it. Every example here is run through lysc check when the page is built — the build fails if one does not compile. Where a claim is about something subtle, the page says how it was measured.

Three ideas run through the whole language, and most surprises dissolve once you have them:

• Music lives inside a part. A file is a set of declarations. A bare note at the top level is an error, and that is what lets a top-level key or time always mean “the file's default” with no ambiguity.
• Order carries meaning; clauses do not. A score is a vertical stack of bands. A lyric row under a staff is that staff's verse because it is under it — not because a clause says so.
• Anything that changes the playing order lives in the form. Repeats and endings are written there, never among the notes.

There is one canonical way to write each idea. Where the language could have been clever it is usually explicit instead.