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Letting types reject impossible states v1.0.0

Use this resource to design types that prevent inconsistent states

New

  • 313 downloads
  • 216 likes
  • 158 saves

Free

Install with the CLI

In a terminal, from the folder you want:

npx --yes palatekit@latest install make-illegal-states-unrepresentable

With no option, the skill goes to ~/.agents/skills/; add --agent claude-code (or codex, cursor…) to target an agent.

First time: connect the CLI with

npx --yes palatekit@latest login

The agent separates semantic primitives with branded types, parses external data at the boundary and requires every variant to be handled. It prefers removing error cases to multiplying handlers.

Mostly picked by

Updated November 2, 2026

Card for the “Letting types reject impossible states” skill

Details

Works in
Install guides
Generates with
Your agent's model
Licence
MIT

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What you get

  • SKILL.md: rules for branded types, parsing and exhaustive variants
  • SKILL.md: how to derive types from an authoritative schema

Good fit for

  • Two string identifiers get mixed up in one function
  • An order status can take an impossible combination

Not for

    Tags

    • typing
    • invariants
    • modeling
    • safety

    About

    You say

    “Separate the user and order identifiers in this signature so they cannot be confused.”

    Card for the “Letting types reject impossible states” skill

    Skill published by backnotprop under the MIT license, delivered in its original version.

    Show more

    How to use it

    1. Install the skill in your agent's skills folder
    2. Ask your agent to design types that prevent inconsistent states
    3. Review and adjust the result

    Content preview

    Files

    • LICENSE1.1 KB
    • NOTICE-PALATEKIT.md0.5 KB
    • SKILL.md1.5 KB

    Origin and licence

    Listed unmodified

    Author
    backnotprop
    Source
    github.com/backnotprop/pstack/tree/23707a30f9cd2f12edef61f2506e2222e30b35aa/skills/principle-type-system-discipline
    Licence
    MIT

    Notice

    « principle-type-system-discipline » (backnotprop, MIT) livré dans sa version d'origine : fiche en français et en anglais par PalateKit.

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