#44th of 34 in Code review and testing
bend
Dependent-typed language where AI-written code must prove rules in LAWS.bend
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- Stars
- 25k
- License
- Apache-2.0
- Last commit
- Nov 2026
- Last release
- Nov 2026
- Language
- TypeScript
18,999 on 21 Apr 202624,978 on 10 Nov 2026
From GitHub's daily star counts.
Checked on GitHub.
Overview
Bend 2 is a Python-like language with dependent types and a proof checker, compiling to C, Metal, CUDA and JavaScript. Rules are declared in a LAWS.bend file, and the agent runs `bend PROOF.bend` after each edit so the compiler rejects changes that break a law. Divide-and-conquer calls run in parallel across CPU cores or a GPU.
Who it is for: Engineers using coding agents who want compiler-enforced correctness rules
Ranked among open-source alternatives to CodeRabbit (#4 of 10).
Strengths
- Laws are machine-checked, so agent edits that violate them fail to compile
- Parallel execution on CPU cores or GPU without threads, locks or kernels
- Installs with one curl script; agent setup is a short AGENTS.md snippet
- Targets C, Metal, CUDA and JavaScript; JS target suits fast iteration
Weaknesses
- Compiler is about 99% AI-written and not fully audited; README warns to expect bugs
- Proofs need real effort: no tactics or proof search, and all code is annotated
- No native Windows support (WSL only); native builds need clang 14+, GPU runs need 19+
- No TLS, HTTP, JSON or regex libraries; numbers limited to Nat, U32 and F32
What it needs
- GPU optional
- Needs clang 14+ (19+ for GPU calls), Metal or CUDA 12 for GPU, X11 and ALSA headers (Linux, window/audio)
Quick answers
Is bend open source?
Yes. Its code is on GitHub under the Apache-2.0 license.
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