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Agent skill

Defining Clos Classes

by ultralisp in ultralisp/ultralisp

A skill your agent uses when defining CLOS classes and their constructors in Common Lisp, adding an optional slot to an existing class, or converting a defstruct to a defclass — especially when…

No licenceAuto-check passedDevelopment

Install Defining Clos Classes

skills CLI
$ npx skills add ultralisp/ultralisp --skill defining-clos-classes -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install ultralisp/ultralisp defining-clos-classes --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/ultralisp/ultralisp.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/defining-clos-classes .claude/skills/defining-clos-classes && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
defining-clos-classes
GitHub stars
258
Token cost
~1k tokens
SKILL.md length
411 words
Files
1
Skills in repo
14
Repo updated
First seen
Licence
None found

At a glance

A skill your agent uses when defining CLOS classes and their constructors in Common Lisp, adding an optional slot to an existing class, or converting a defstruct to a defclass — especially when…

  • Defining CLOS classes and their constructors in Common Lisp
  • SKILL.md covers Overview, When to Use, Use defclass, not defstruct and The constructor pattern (the…, plus 5 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Adding an optional slot to an existing class

What it does

Defining Clos Classes is an agent skill from ultralisp/ultralisp. Use when defining CLOS classes and their constructors in Common Lisp, adding an optional slot to an existing class, or converting a defstruct to a defclass — especially when writing a make-<name constructor that hides make-instance.

Its SKILL.md is about 1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Development. The repository describes itself as: The software behind a Ultralisp.org Common Lisp repository.

When your agent uses it

  • Defining CLOS classes and their constructors in Common Lisp
  • Adding an optional slot to an existing class
  • Converting a defstruct to a defclass — especially when writing a make-<name constructor that hides make-instance

Example prompts

  • “/defining-clos-classes”

What it can do on your machine

Read from SKILL.md and the folder at commit 3439788. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are lisp).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Defining Clos Classes loads about 1k tokens when it runs. Until then it costs about 64 tokens; SKILL.md has 411 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~64
When it runs · the whole SKILL.md, loaded when a task matches
~1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

Without a licence we can't republish the file, so here is its outline and opening line. It has 411 words (~1,029 tokens).

“Every data type in these projects is a defclass with a constructor function make- that hides make-instance. The constructor takes &rest restargs so it never duplicates the class's :initform defaults.”

— opening of SKILL.md by ultralisp
name
defining-clos-classes

Read the full SKILL.md on GitHub

Files

Just SKILL.md in .agents/skills/defining-clos-classes of ultralisp/ultralisp.

Open the folder on GitHubat commit 3439788

Compare with similar skills

Defining Clos Classes next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Defining Clos Classes compared with similar skills
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Defining Clos Classes this skillultralisp/ultralisp258—~1kAutomated safety check: PassNone
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Typescript Advanced Typesrolling-scopes/rsschool-app10k25 repos~4.2kAutomated safety check: PassMPL-2.0
PR Babysitteropeninterpreter/openinterpreter69k3 repos~4.2kAutomated safety check: PassApache-2.0
Code Review ChecklistshareAI-lab/learn-claude-code78k5 repos~1.1kAutomated safety check: PassMIT

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Categories

Questions about Defining Clos Classes

What does Defining Clos Classes do?

A skill your agent uses when defining CLOS classes and their constructors in Common Lisp, adding an optional slot to an existing class, or converting a defstruct to a defclass — especially when…. Defining Clos Classes is an agent skill from ultralisp/ultralisp. Use when defining CLOS classes and their constructors in Common Lisp, adding an optional slot to an existing class, or converting a defstruct to a defclass — especially when writing a make-<name constructor that hides make-instance.

When should I use Defining Clos Classes?

Defining Clos Classes fits situations like: defining CLOS classes and their constructors in Common Lisp; adding an optional slot to an existing class; converting a defstruct to a defclass — especially when writing a make-<name constructor that hides make-instance.

How do I install Defining Clos Classes in Claude Code?

Run `npx skills add ultralisp/ultralisp --skill defining-clos-classes -a claude-code`. Or copy the skill folder (.agents/skills/defining-clos-classes in ultralisp/ultralisp) into .claude/skills/defining-clos-classes in your project. Claude Code loads it when a task matches its description.

How do I install Defining Clos Classes in Codex?

Run `npx skills add ultralisp/ultralisp --skill defining-clos-classes -a codex`. Or copy the skill folder (.agents/skills/defining-clos-classes in ultralisp/ultralisp) into .agents/skills/defining-clos-classes in your project. Codex loads it when a task matches its description.

Can I use Defining Clos Classes in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add ultralisp/ultralisp --skill defining-clos-classes -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/defining-clos-classes, .gemini/skills/defining-clos-classes, .github/skills/defining-clos-classes and .opencode/skills/defining-clos-classes in your project.

What does Defining Clos Classes need to run?

SKILL.md names no scripts, command-line tools or credentials: Defining Clos Classes is instructions for the agent only.

Does Defining Clos Classes access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Defining Clos Classes safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Defining Clos Classes use?

No licence was found for Defining Clos Classes or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.

How many tokens does Defining Clos Classes use?

About 1k tokens (SKILL.md is roughly 4.1k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Defining Clos Classes?

Skills that share tags, products or a category with Defining Clos Classes: Vercel Composition Patterns (supabase/supabase, 111k stars), Finishing a Development Branch (obra/superpowers, 296k stars), Typescript Advanced Types (rolling-scopes/rsschool-app, 10k stars) and PR Babysitter (openinterpreter/openinterpreter, 69k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Defining Clos Classes?

ultralisp (a GitHub organization) maintains it in ultralisp/ultralisp, which has 258 GitHub stars. The repository holds 14 skills in this directory. The repository was last updated on September 13, 2026.

Source: ultralisp/ultralisp on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.