HMSL - Hierarchical Music Specification Language
HMSL is a programming language for experimental music composition and performance. It was actively developed between 1986 to 1996. HMSL is an object oriented set of extensions to the Forth language for the Amiga and the Macintosh.
Download HMSL DMG Installer for Mac OS. Released Oct 1, 2026
Explore the Guided Tours on GitHub.
HMSL was created by Phil Burk, Larry Polansky, and David Rosenboom at the Mills College Center for Contemporary Music. It was distributed by Frog Peak Music.
The original distribution is out of print. But the source code is available on GitHub and has been ported to modern day Macintosh. We plan to also port HMSL to Windows and Linux.
Overview of HMSL.
Downloadable examples, fixes, and the HMSL DSP code.
HMSL mailing list, Google group
Screenshot of HMSL Terminal and Shape Editor.
News
- Oct 1, 2026 - Release of signed installer for Mac OS.
- Oct 30, 2015 - The Whitechapel Gallery in London hosted an exhibit on HMSL curated by Luke Fowler. It contains concert notes, correspondance, documentation, artifacts, videos, and a listening room. The exhibit ran through Feb 7, 2016. See photos here.
Call for Contributions
If you are an HMSL programmer and would like to share your software, writings, or HMSL generated General MIDI files on this web site, please contact us on GitHub Discussions.