BPscript — A Modern Language for the Bol Processor

BPscript is a research-driven composition language built on the Bol Processor (BP3) — the formal music grammar system Bernard Bel and Jim Kippen have developed since 1981, originally to model North Indian tabla improvisation.

BP3 has an unusually wide range of formal power: depending on which mechanisms are active, its grammar spans context-free (Type 2) to context-sensitive (Type 1) and beyond — a tunable complexity rather than a fixed class. It is also bidirectional: it can generate music and recognize whether a sequence belongs to a musical language (PROD/ANAL modes), a reversibility rarely found in music systems. Forty years of work gave it weighted stochastic grammars, native polymetry, conditional flags, master/slave patterns, seven derivation modes, and dozens of performance-control functions. TidalCycles cites it as an influence.

That power has always been locked behind a dense, archaic syntax and a 1990s C codebase. BPscript is the research effort to keep the formalism and modernize everything around it:

• A readable, typed language — 3 reserved words, 24 symbols, 9 flag operators. Typed temporal primitives (gate, trigger, cv), scenes, actors, declarative I/O mappings.
• Native code via backticks — embed runtime-evaluated code (currently JS / Web Audio) alongside the temporal structure, in a single file.
• Compiles to BP3 — the transpiler emits native BP3 grammar, so 40 years of derivation expertise are reused, not reinvented. The engine runs in the browser via WebAssembly.
• An evolution path — BPx, a next-generation reactive derivation engine designed to succeed BP3's batch C core (see docs/design/BPX_ENGINE_SPEC.md).

Try it online: roomi-fields.com/bpscript — write BPscript, compile to a BP3 grammar, and derive it in the browser.

Setup

git clone --recursive https://github.com/roomi-fields/BPscript.git
cd BPscript

# Recompile the engine (requires Emscripten + GCC + mingw)
cd bp3-engine
source /path/to/emsdk/emsdk_env.sh
./build.sh all --archive --version=v3.4.4-wasm.1
cd ..

# Run the regression tests
node test/test_all.cjs --bin last

Structure

bp3-engine/          BP3 WASM engine (submodule roomi-fields/bp3-engine, branch wasm)
src/
  transpiler/        Tokenizer, parser, encoder (BPscript → BP3 grammar)
  bpx/               BPx engine stub (next-generation derivation engine)
lib/                 JSON libraries (controls, alphabets, tunings, filter, routing)
dist/                BP3 WASM binaries (bp3.js, bp3.wasm, bp3.data)
test/                Test infrastructure S0→S5 (36 reference grammars)
docs/                Specification, design, and reference documentation
scenes/              Example .bps files

Pipeline

Source .bps → Tokenizer → Parser (AST) → Encoder → BP3 grammar + alphabet + prototypes
                                                          ↓
                                              BP3 WASM engine (produce)
                                                          ↓
                                                    Timed tokens

The timed tokens are the language's output. A downstream runtime (scheduler, audio, MIDI/OSC) consumes them — out of scope for this repository.

Test

Prerequisite: build the engine with ./build.sh all --archive (see Setup).

The tests compare BP3 engine production across 6 stages:

Stage	Source	Description
S0	bp.exe (Windows)	Bernard's PHP reference
S1	bp3 (native Linux)	Same engine, different platform
S2	bp3.wasm	MIDI events from WASM
S3	bp3.wasm	Timed tokens from p_Instance
S4	bp3.wasm	Like S3 with silent sound objects
S5	transpiler + bp3.wasm	Full BPscript pipeline

# Run all tests (requires --bin)
node test/test_all.cjs --bin last

# Test a specific grammar
node test/s1_native.cjs drum --bin last
node test/s4_wasm_silent.cjs drum --bin last

# The "last" tag reads builds/LAST in bp3-engine

The 36 reference grammars live in test/grammars/grammars.json. Each stage's snapshots are in test/grammars/{name}/snapshots/.

Detailed results: test/RESULTATS.md Open points with Bernard: test/FEEDBACK_BERNARD.md

Documentation

Start with docs/INDEX.md (full index). Highlights:

• docs/spec/LANGUAGE.md — complete language specification
• docs/spec/EBNF.md — formal grammar (ISO 14977)
• docs/spec/AST.md — AST node reference
• docs/design/ARCHITECTURE.md — compilation pipeline
• docs/design/BPX_ENGINE_SPEC.md — next-generation engine spec
• docs/reference/BP3_FILE_FORMATS.md — BP3 auxiliary file formats
• BACKLOG.md — open points and backlog