In 1985, I embraced the launch of the Amiga 1000. Among many other fun
uses, it became the center of my little synth "studio", doing MIDI
sequencing, being patch librarian, and sometimes patch editing (after
at least one commercial package, I had tried to write a program that
helped me specify additive harmonics and envelopes for the Kawai K-5,
which barely worked and was never much finished). One strange little
sidebar in an otherwise typical 1980s MIDI setup was HMSL.

The Hierarchical Music Specification Language (HMSL) is a
domain-specific language for music composition and synthesis, built as
an object oriented set of extensions to Forth. This grew out of work
at the Mills College Center for Contemporary Music, as a collaboration
between David Rosenboom (https://davidrosenboom.com), Larry Polansky,
and James Tenney.

HMSL has roots in other early theoretical computer music languages (it
would not be entirely unfamiliar to MUSIC-descended languages), but with
a strong emphasis on structural composition and real-time performance.

They later worked with Phil Burke, who was doing some early hardware
explorations, and joined forces to produce a portable version of HMSL
that added OOP techniques to the language. It was then ported to the
Amiga where it was eventually married to that platform's excellente
JForth, and gained the ability to use the Amiga's native sound hardware
as well as MIDI interfaces. Later, HMSL was ported to the Macintosh
where even more features were added.

A very interesting part of HMSL's pedigree is an early version used by
Rosenbloom in the unique Buchla TOUCHE, a digital/analog hybrid synth
that broke the Buchla tradition to include a standard piano-style
keyboard. Rosenbloom worked with Doug "Lynx" Crowe to include
performance features along with the PATCH-IV language that controlled
the synth's voice architecture.

The early Amiga and Macintosh versions were distributed by Frog Peak
Music, but original disks are hard to come by. Phil Burke (who now
works for Google, adding audio and MIDI features to Android) has built on
pieces of HMSL over the years, and returned to porting it to modern
native platforms in open source form
(https://github.com/philburk/hmsl).

I've spent a few hours spread over several weekends seeing if I could
get the latest HMSL to compile on a non-MacOS platform (MacOS is the
only platform for which binary releases are provided). Overcoming
mostly configuration obstacles (Phil's beginning attempts at full
CMake support are incomplete as of this writing), I hit a bit of a
wall when I discovered that a blocking I/O library built on top of
Portaudio seems to be using some obsolete Portaudio constructs
(PortAudioStream?). I'm wondering if, among the various projects
stitched together, it is depending on an earlier version of
Portaudio.

In any case, I'm taking a break on that path for a while since I'm
pretty happy right now with Common Music (CM3,
https://commonmusic.sourceforge.net/). Perhaps more on this wonderful
package later.

Still, if you have the opportunity to play with HMSL, give it a look.
I recall it just felt nimbler than the other non-real-time languages
prevalent at the time.