tree-sitter-flow

Tree-sitter grammar source for the Flow programming language.

This integration is kept in the main Flow repository until it is useful to split it into a dedicated tree-sitter-flow repository. The grammar targets the stable language core and the commonly used experimental evolution surface.

Validate

cd third_party/integrations/tree-sitter-flow
npm install
npm test

npm test runs tree-sitter generate and the corpus suite in test/corpus/. For a broader check, parse the repository's own Flow sources and look for ERROR nodes:

find /path/to/flow -name '*.flow' > /tmp/flow-files.txt
npx tree-sitter parse --paths /tmp/flow-files.txt -q

As of this revision the grammar parses the full in-tree corpus cleanly. The only remaining ERROR results are intentional parse-failure fixtures (tests/*/fixtures/*bad*, parse_error.flow, syntaxerr.flow) and tests/lang/test_prefix_deref.flow, whose *p = 7 statement after an expression line relies on Flow's indentation-aware disambiguation between a binary * continuation and a dereference statement.

Use

The grammar identifies *.flow files with scope source.flow. Highlight queries live in queries/highlights.scm.

The language specification remains authoritative. If this grammar and the compiler disagree, fix the grammar rather than changing compiler behavior to satisfy editor tooling.

Upstream path

Once this grammar has generated cleanly against representative Flow sources, publish it as a dedicated repository and use that repository for Helix, Zed, Neovim and other Tree-sitter consumers. The dedicated repository should check in generated parser sources and tag releases.