Velato is a language where one writes code with music, in the form of a MIDI file. Read more on esolangs: http://esolangs.org/wiki/Velato

This is in Lilypond format. It needs to be converted to a MIDI file to be read by the Velato compiler:

\version "2.24.3"
melody = \relative c' {
\clef treble
\key c \major
\time 4/4

  c			% set root
  a g			% print
  e f			% a character 
  a dis		        % value of 'H' (72) 
  g			% end of char marker
  c			% the root note does nothing the second time but can be used between commands
  a g			% print
  e f			% a character 
  d cis fis	        % value of 'i' (105)
  g			% end of char marker
  c			% an extra c because why not
}

\score {
\new Staff \melody
\midi { }
}

Version 2 of Velato was re-written from the ground up, using NAudio and a saner parsing strategy. Significant changes:

• Supports micro-tuning variants of the language
• Can transpile to C# or JavaScript code
• Looks at the first MIDI track, rather than the first channel (more in line with how MIDI is used)
• Examples are in the (more widely used) Lilypond, rather than the GUIDO system