flow-compiler

The Flow language compiler, written in Flow.

This repository holds the self-hosted flowc. The compiler that compiles Flow is itself a Flow program. The aim is that the whole pipeline lives here in Flow: the front end (lexer, parser, type checker), the C transpilation layer, and the MLIR lowering layer. The Python host in the main flow repository stays as the reference until each layer is ported and verified here.

Status

• Transpilation layer (Flow to portable C): present and self-hosting. The bootstrap compiles itself to a three-generation byte-identical fixed point.
• Language corpus: 103 of 126 tests/lang files compile and run through the self-hosted compiler on the Linux CI runner (104 on macOS; the one difference, test_geometry_diagram, is platform-dependent). The rest are the known gaps (closures, effects, generics, time blocks) tracked for the port.
• MLIR lowering layer: in Flow and growing. compiler/src/mlir_gen.flow emits the func, arith, scf, and memref dialects under FLOWC_BACKEND=mlir. Faithful coverage: integer arithmetic and comparisons, local bindings and assignments, unary minus, integer function calls (func.call), pure-float functions (arith.addf/etc), and control flow (if/while/for via memref slots and scf). Anything outside the covered subset emits a valid typed stub. mlir-opt verifies the output. The full plan is in docs/MLIR_PORT.md.

Build

The checked-in compiler/bootstrap/flowc_stage_a.c is the seed. Build it with any C11 compiler, then use it to compile Flow.

mkdir -p compiler/build
cc -O2 -o compiler/build/flowc_bootstrap compiler/bootstrap/flowc_stage_a.c

Compile one Flow file to C and run it:

BOOT=compiler/build/flowc_bootstrap
FLOWC_BUNDLE=1 FLOWC_DIR=. FLOWC_IN=tests/lang/test_arithmetic.flow \
  FLOWC_OUT=/tmp/out.c "$BOOT"
cc -O0 -o /tmp/out /tmp/out.c -Itests/lang
/tmp/out

Run the whole language corpus:

BOOT=compiler/build/flowc_bootstrap
for f in $(find tests/lang -name '*.flow' | sort); do
  FLOWC_BUNDLE=1 FLOWC_DIR=. FLOWC_IN="$f" FLOWC_OUT=/tmp/out.c "$BOOT" \
    && cc -O0 -o /tmp/out /tmp/out.c -Itests/lang \
    && echo "ok   $f" || echo "FAIL $f"
done

Layout

Path	Contents
compiler/src/	The compiler, in Flow: lexer, parser, type checker, C backend
compiler/src/mlir_gen.flow	The MLIR lowering backend (func/arith), in Flow
compiler/bootstrap/	The seed C (flowc_stage_a.c) and its built binary
compiler/scripts/	Bootstrap regeneration and self-host verification
compiler/host/	The C driver that hosts the Stage-A compiler
tests/lang/	The language corpus, the self-host regression target
docs/MLIR_PORT.md	The Python-to-Flow port plan for the MLIR layer

Bootstrap regeneration

Editing anything under compiler/src/ means the checked-in bootstrap C must be regenerated so it stays a fixed point. See AGENTS.md.

Continuous integration

CI runs on GitHub Actions because this repository is public and the free runner keeps the build off local machines. It builds the bootstrap and runs the corpus against a baseline that fails on regression.

License

Proprietary. All rights reserved. See LICENSE. The source is published for visibility and CI. For licensing inquiries, contact abhishek.shivakumar@gmail.com.