# Fastmod

> Use fastmod to make mass code updates to avoid many repetitive changes.

- Skill: `pydantic/fastmod` (Agent Skill)
- Install (CLI): `npx skillmds@latest add pydantic/fastmod`
- Raw SKILL.md: https://api.skillmd.com/api/skills/pydantic/fastmod/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: pydantic (https://skillmd.com/u/pydantic)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/pydantic/fastmod

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# fastmod

## Instructions

You can occasionally use `fastmod` or `sed` to make mass updates to the codebase and avoid wasting tokens changing each case one at a time.

Before making many repetitive changes to the codebase, consider using `fastmod --accept-all`.

THINK HARD about how best to use `fastmod` as it can dramatically improve your productivity.

## Examples

Example of switching the `py_type` function to take `heap: &Heap` instead of a generic `H: HeapAccess` parameter:

```bash
fastmod --accept-all 'fn py_type<H: HeapAccess>\((.+?), heap: &H\b' 'fn py_type($1, heap: &Heap'
```