In 1996, James McCartney released SuperCollider. Over the next three decades, it became the foundational construct of academic computer music — university courses taught with it, the TOPLAP community performed in it, sound art installations ran on it. It has an object-oriented class library (sclang), a separate audio server (scsynth), a GUI framework, an IDE, message-passing, inheritance chains, hundreds of UGens. It is a building: solid, complete, named. It is construct.

In January 2025, McCartney open-sourced sapf — "Sound As Pure Form." This is not SuperCollider's next version, not a successor, not an extension. It is a chisel taken to SuperCollider. McCartney chiseled away the object-oriented paradigm and left the stack. Chiseled away the client-server architecture and left a single process. Chiseled away the GUI and left the terminal. Chiseled away the class library and left built-in functions. Chiseled away syntax — postfix notation is "the least syntax possible," in his own words. After all the chiseling, what remains? Auto-mapping over lazy sequences. Function composition as concatenation. Sound itself.

sapf's lineage is a double remainder. APL (1962, Iverson) is the remainder of mathematical notation — when array operations execute directly without element-by-element loops, what survives is a disproportionate density of expressive power. Forth (1970, Moore) is the remainder of programming language design — when you chisel away all syntax until only the stack and words remain, what survives is composition-as-concatenation. Both languages are "widely derided as write-only languages" — McCartney quotes this in his README, then immediately cites Alan Perlis: "What attracted me to APL was a feeling that perhaps through APL one might begin to acquire some of the dimensions in programming that we revere in natural language — some of the pleasures of composition; of saying things elegantly; of being brief, poetic, artistic." sapf merges these two remainder lineages: Forth's stack brings left-to-right pipeline transformation (no more inside-out nesting of parentheses); APL's auto-mapping brings pervasive operations over lazy sequences. Sound events are represented as possibly infinite lazy lists. Short programs achieve results out of proportion to their size.

The deepest remainder structure here is this: the creator chiseling his own construct. McCartney is not critiquing someone else's work — he is deconstructing his own most famous creation. SuperCollider is already construct: it has a community, forums, academic citations, UNESCO-recognized cultural practice (live coding). McCartney walked out of that building, not to build a bigger one, but to dig below the foundation and find the minimum thing that can still make sound. The answer: a stack, lazy sequences, auto-mapping, postfix notation. Twenty-six commits. 934 stars. No release schedule, no roadmap, no business model. A cross-platform fork (ahihi/sapf, 122 commits) is growing on Linux and Windows. Editor plugins (Emacs, Neovim, VS Code) are being built spontaneously by the community. scsynth.org has a dedicated sapf subforum. Every part of the ecosystem was grown independently by a different person — this is not a product launch, this is a remainder growing on its own.

Seeing sapf now matters more than seeing it later. Because it sits in the naming gap: the SuperCollider community partially claims it, but sapf explicitly rejects SuperCollider's paradigm. The APL community might appreciate its auto-mapping, but it is not APL. The Forth community might appreciate its stack, but it is not Forth. Music technology press has not noticed it. The art world has no idea it exists. It is not a programming language, not a synthesizer, not a composition tool, not a live coding environment — or rather it is all of these simultaneously, but no single name can fully cover it. Its logic is still growing. When it acquires a stable name, it will become construct. Right now, it is remainder.

Han Qin (秦汉) · @hqinjarsy · SAE Judgment & Aesthetics