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Julia Syntax Lowering

Development
julia-syntax-lowering

Julia Syntax Lowering is an Agent Skill for development published in the JuliaLang/julia repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.

Develop and test JuliaSyntax and JuliaLowering in Julia's source tree. Use when modifying JuliaSyntax/ or JuliaLowering/, running package or targeted tests, or checking JuliaLowering execution.

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How to use this skill

Bring this guide into your coding agent with a prompt tailored to the tool you use.

  1. Open your project in Codex.
  2. Copy and paste the prompt below.
  3. Review files and risks before approving any action.
Prompt to paste
Inspect the Agent Skill at https://github.com/JuliaLang/julia/blob/HEAD/doc/src/devdocs/agents/skills/julia-syntax-lowering/SKILL.md and all supporting files. Report provenance, permissions, scripts, dependencies, and security risks. Propose an exact installation into .agents/skills/julia-syntax-lowering, but wait for my approval before writing files or running scripts.

Copying this prompt does not install or run the skill. Review third-party files before use.

JuliaSyntax & JuliaLowering development

Use this when modifying JuliaSyntax/ or JuliaLowering/ source, tests, or package metadata.

Testing JuliaSyntax

Run package tests from the repository root:

julia --project=JuliaSyntax -e 'using Pkg; Pkg.test()'

JuliaSyntax is not tied only to the in-tree Julia runtime; if a change may be version-sensitive, test it with the relevant installed Julia version(s).

Testing JuliaLowering

Prefer the in-tree Julia runtime because compatibility with the Julia runtime may matter:

./usr/bin/julia --project=JuliaLowering -e 'using Pkg; Pkg.test()'

If ./usr/bin/julia is unavailable, note that limitation and use an available julia executable only for preliminary validation.

In this repository, JuliaLowering/Project.toml points its JuliaSyntax dependency at the sibling JuliaSyntax checkout (path = "../JuliaSyntax"). Therefore, JuliaSyntax changes can affect JuliaLowering. When a JuliaSyntax change may affect lowering behavior or syntax data consumed by JuliaLowering, run the JuliaLowering test command as well.

Targeted JuliaLowering tests

For targeted JuliaLowering test execution, include JuliaLowering/test/utils.jl before the test file, matching JuliaLowering/test/runtests.jl:

./usr/bin/julia --project=JuliaLowering -e 'cd("JuliaLowering/test") do; include("utils.jl"); include("scopes.jl"); end'

For _ir.jl fixtures, call test_ir_cases after loading utils.jl:

./usr/bin/julia --project=JuliaLowering -e 'cd("JuliaLowering/test") do; include("utils.jl"); test_ir_cases("scopes_ir.jl"); end'

Trying JuliaLowering execution

For quick execution checks, run with the in-tree Julia runtime and the JuliaLowering project:

./usr/bin/julia --project=JuliaLowering

Then either evaluate code explicitly through JuliaLowering:

using JuliaLowering
JuliaLowering.include_string(Main, "1 + 2")

or activate JuliaLowering as the process lowerer, then evaluate subsequent code normally:

using JuliaLowering
JuliaLowering.activate!()

1 + 2

Use include("path/to/file.jl") after activation when checking a file. When using JuliaLowering.activate!() from -e, make the code under test a separate top-level statement after activation, or put it in include(...).