Hemlock2-Coder-7B-GRPO
hemlang/Hemlock2-Coder-7B improved with execution-reward GRPO (grimoire ≥ 2.0 / hemlock-rl). Completions were executed in the Hemlock interpreter's sandbox and rewarded for exactly reproducing verified reference stdout.
Strictly improves the base model on hembench (zero-shot, n=5, benchmark-overlapping training tasks held out):
| pass@1 | pass@5 | |
|---|---|---|
| Hemlock2-Coder-7B | 28.9% | 55.3% |
| Hemlock2-Coder-7B-GRPO | 36.8% (+7.9) | 57.9% (+2.6) |
Largest gains in syntax (L1 pass@1 2/9 → 4/9, pass@5 7/9 → 8/9) and systems/concurrency (L4 pass@1 1/7 → 3/7).
Training
- Method: GRPO (LoRA r=16 α=32, β=0.1 KL vs frozen base, G=8, dynamic sampling, unscaled advantages), 186 deduplicated prompts × 3 epochs.
- Rewards: sandboxed execution; exact stdout match vs verified reference = 2.0, runs-but-wrong = 0.5, error = −0.5, no code / timeout = −1.0.
- Data: execution-verified translation/generation tasks (now published as hemlang/hemlock-codex3-SFT), one language-variant per task, hembench-name-overlapping tasks excluded.
Q8_0 GGUF included.