# Principle Type System Discipline (agent skill)

> Principle Type System Discipline is an agent skill (a SKILL.md file) from backnotprop/pstack. Apply when designing types, reviewing a function signature, or writing code in any statically-typed language. It works with Claude Code, Codex, Cursor and OpenCode and has 1,172 GitHub stars across a repository of 2 listed skills.

Apply when designing types, reviewing a function signature, or writing code in any statically-typed language. Make illegal states unrepresentable, brand semantic primitives, parse external data at boundaries, refuse to lie to the compiler, exhaust variants, derive from authoritative schemas. The type checker is a proof assistant. Use it to eliminate impossible states, mismatched primitives, and unhandled variants at compile time.

## Key facts

| Fact | Value |
|---|---|
| Repository | https://github.com/backnotprop/pstack |
| Skill path | skills/principle-type-system-discipline/SKILL.md |
| Skill name | principle-type-system-discipline |
| GitHub stars | 1,172 |
| Installs on skills.sh | not listed |
| License | MIT |
| Skills in repo | 2 |
| Plugin marketplace | no |
| Official | no |
| Works with | Claude Code, Codex, Cursor, OpenCode |
| Category | Docs & writing |
| Last commit | Oct 4, 2026 |

## Add this skill

### Claude Code

```sh
git clone --depth 1 https://github.com/backnotprop/pstack.git
cp -r pstack/skills/principle-type-system-discipline ~/.claude/skills/principle-type-system-discipline   # personal, or .claude/skills in a project
```

In the Claude apps, zip the skill folder and upload it under Customize > Skills > + > Upload a skill (code execution must be on).

### ChatGPT / Codex

```sh
git clone --depth 1 https://github.com/backnotprop/pstack.git
cp -r pstack/skills/principle-type-system-discipline .agents/skills/principle-type-system-discipline   # repo; ~/.agents/skills for all projects
```

### Cursor

```sh
git clone --depth 1 https://github.com/backnotprop/pstack.git
cp -r pstack/skills/principle-type-system-discipline .cursor/skills/principle-type-system-discipline   # project; ~/.cursor/skills for all projects
```

Sources (checked 2026-10-07): https://code.claude.com/docs/en/skills, https://support.claude.com/en/articles/12512180-using-skills-in-claude, https://learn.chatgpt.com/docs/build-skills, https://cursor.com/docs/context/skills

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Canonical page: https://appsgit.com/skills/backnotprop-principle-type-system-discipline
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