01

Install

Lily# works inside Visual Studio Code, a free editor. Two downloads, a few minutes, and nothing else to set up — no programming and no command line. (For the curious: the extension brings its own runtime, compiler and fonts — Emmentaler, three SMuFL music fonts and the TeX Gyre text faces.)

1. Get Visual Studio Code — free Lily# runs inside Visual Studio Code, a free editor from Microsoft (“VS Code”). You don't need to know programming to use it: here it is simply the window you write music in. On its website, click the download button for your computer — Windows, Mac or Linux — open the file that downloads, and accept the installer's suggestions.
2. Add Lily# to it Start VS Code. On its left edge, click the Extensions icon — four small squares, one coming loose — or press Ctrl+Shift+X (Cmd+Shift+X on a Mac). Type Lily# in the search box at the top, and click Install next to Lily# by yotsuda. Everything it needs comes with it, the music fonts included; there is nothing else to download.
3. Start a score In the menu, choose File → New File… and pick Lily# Score (.lys). A short tune appears on the left, and its printed score on the right. Change a note on the left and the score changes as you type. Save it with File → Save, under a name that ends in .lys (my-song.lys).
4. Hear it Click the score once, then press ▶ at its top: it plays, and each note lights as it sounds. (A computer lets a page make sound only after you have clicked in it — that first click is what it waits for.) Out of the box it uses the instrument sounds your computer already has; for fuller ones, install a free sound font — a download and a few clicks.
5. Learn the rest as you go On an empty line at the end of the file, type lesson and press Ctrl+Space: a list of twelve short lessons appears. Pick lesson-01-completion to begin — it takes the place of the tune (VS Code asks first) and shows you one thing at a time. The same lessons are on the Learn pages.

02

A first score

New Score gives you this file, with the title selected so you can type over it:

title "Untitled"

tempo 100
time 4/4
key c major

part melody {
  clef treble
  section A { c'4 d e f | g2 g | }
}

form { A }

score {
  staff melody
}

Read it from the top: the piece's settings, then a part (who plays) holding a section of music, then the form (in what order the sections play) and the score (what is printed). The music is c'4 d e f | g2 g |: note names, a duration after a note (4 a quarter, 2 a half) that the next notes keep until you write another, and | at each bar line.

• Change a note — the score redraws as you type, not when you save. Put the caret on a note: it lights up in the score, and sounds.
• Add a bar — type e4 d c2 | before the closing brace.
• Hear it — press ▶ at the top of the preview. Alt+P plays the note under the caret, Alt+M the bar.
• Make a mistake — type a bar that is too long. A squiggle appears; hover it to read what is wrong, and the lightbulb (Ctrl+.) fixes it where there is one obvious repair.
• Export — Lily#: Export as PDF (or SVG, PNG, MIDI, MusicXML, LilyPond) from the command palette or the preview.

03

The lessons

Twelve short lessons live in the editor. On an empty line at the top level of a .lys file, type lesson and press Ctrl+Space: picking one puts it in the file. Each is a playable score with its steps marked in red in the preview — completion and the preview, notes and octaves, rhythm, keys, expression, form and repeats, lyrics, chords, piano, drums, a band, and a jazz chart. The same lessons are on the Learn pages.

04

Where next