---
license: apache-2.0
task_categories:
- text-generation
language:
- en
tags:
- hemlock
- dpo
- orpo
- preference
- code
pretty_name: Poison-DPO
---

# Poison-DPO

Preference pairs for de-biasing Hemlock code models away from **Python/JS habits**
("poison") and toward idiomatic Hemlock.

Each row is a minimal pair:
- `chosen` — clean, idiomatic Hemlock that **runs** under the interpreter.
- `rejected` — the *same program* with **one** Python/JS-ism injected, verified to
  **fail** (parse/runtime error) or produce different output.

Because chosen and rejected differ by exactly one idiom, the preference signal
(DPO/ORPO odds-ratio) isolates the specific behavior to suppress.

## Coverage

Targets the standard-library / idiom errors a Python/JS-pretrained base reaches for:

| Hemlock (chosen) | Python/JS-ism (rejected) |
|---|---|
| `map.delete(k)` | `map.remove(k)` |
| `map.has(k)` | `k in map` |
| `map.keys()` | `Object.keys(map)` |
| `arr.push(x)` | `arr.append(x)` |
| `print(x)` | `println(x)` |
| `` `${x}` `` (template) | `f"{x}"` |
| `"...json..."` | `'...json...'` (rune-literal trap) |
| `arr.length` | `len(arr)` |
| `s.contains(x)` | `s.includes(x)` |
| `parse()` / `stringify()` | `loads()` / `dumps()` |
| `for (x in arr)` | `for (i in range(len(arr)))` |
| `null` / `fn(x){...}` | `None` / `lambda x: ...` |

## Construction

Every pair was generated and **validated through the Hemlock interpreter**: the
`chosen` must exit 0, and the `rejected` must fail or diverge. Pairs are sourced
from authored idiom templates (deep, targeted coverage) and from corruption of the
real `hemlang/hemlock-formulary-SFT` programs (breadth over actual stdlib usage).

## Schema

```json
{"prompt": "...", "chosen": "<clean hemlock>", "rejected": "<poisoned hemlock>"}
```

Usable directly with ORPO/DPO/SimPO/CPO/IPO (needs `chosen` + `rejected`).