Lean4 Ffi Constructor Layout is a community-contributed Claude Code skill in the general-misc sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/lean4-ffi-constructor-layout/ and loads when your prompt matches the skill's trigger.
When to invoke it: Use when: (1) assertion violation "i < lean_ctor_num_objs(o)" accessing constructor fields, (2) assertion violation "offset >= lean_ctor_num_objs(o) * sizeof(void*)" with scalar getters, (3) lean_ctor_get_uint8/uint16/uint32 crashes or returns garbage, (4) creating FFI bindings for Lean inductives or structures with small integer fields (UInt8, UInt16, UInt32). Covers lean_alloc_ctor, lean_ctor_get, lean_ctor_set, and scalar field offset calculation.
The Lean4 Ffi Constructor Layout Claude Code skill is built for Claude Code users and developers across all disciplines looking for general-purpose AI assistance. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 146,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
mkdir -p ~/.claude/skills/lean4-ffi-constructor-layout curl -L https://claudskills.com/skills/lean4-ffi-constructor-layout/SKILL.md \ -o ~/.claude/skills/lean4-ffi-constructor-layout/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/lean4-ffi-constructor-layout/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/lean4-ffi-constructor-layout/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\lean4-ffi-constructor-layout\SKILL.md on Windows. See the full install guide for step-by-step instructions.
Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →
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SKILL.md from the source repository to ~/.claude/skills/lean4-ffi-constructor-layout/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Lean4 Ffi Constructor Layout is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the General category. Learn more at /learn/what-is-a-claude-skill/.If you reference this skill in a blog post, paper, or documentation, you can cite it as:
@misc{lean4-ffi-constructor-layout-2026,
author = {Claude Code},
title = {Lean4 Ffi Constructor Layout [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/lean4-ffi-constructor-layout/}
}Grade A · scanned 2026-07-06 — free static scan against the OWASP Agentic Skills Top 10.
No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›
Browse all General skills in the ClaudSkills registry, or explore these other picks from the same category:
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SKILL.md files, not affiliated with, endorsed by, or sponsored by Anthropic.