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Effect V4 Module Index

Category: General  ·  Sub-category: legal-compliance  ·  Last updated:
The routing map for Effect v4 core — every module in one table, what it is, when to reach for it, and where to read it in the vendored source. Use FIRST when asking "what module do I reach for", "does Effect have a Sink/Pool/Trie/pattern-matcher", "what is Sink/Channel/Deferred/RcMap for", "where does X live in the source", or before designing ANY capability (the contract-inventory gate greps this map's territory). Opens with a routing-by-task table for the ones people miss by name — spawning a subprocess, a TTL cache with in-flight de-duplication, writing to stdout from a library. Rows route; they do not teach — patterns live in the other effect-v4-* skills, and the source is the authority on signatures and semantics.
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From the source SKILL.md

Every module of effect@4 core, one row each: what it is, when to reach for it. This skill exists so the other skills can stop explaining what things are and spend their space on patterns — and so no one designs a capability core already ships (the effect-v4-planning contract-inventory gate).

What this skill does

Effect V4 Module Index is a community-contributed Claude Code skill in the legal-compliance sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/effect-v4-module-index/ and loads when your prompt matches the skill's trigger.

Who uses this skill

The Effect V4 Module Index 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 196,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/effect-v4-module-index
curl -L https://claudskills.com/skills/effect-v4-module-index/SKILL.md \
  -o ~/.claude/skills/effect-v4-module-index/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/effect-v4-module-index/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/effect-v4-module-index/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\effect-v4-module-index\SKILL.md on Windows. See the full install guide for step-by-step instructions.

Telegram

📱 Install from your phone or desktop Telegram

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 →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Effect V4 Module Index Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/effect-v4-module-index/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the Effect V4 Module Index skill do?
The routing map for Effect v4 core — every module in one table, what it is, when to reach for it, and where to read it in the vendored source. Use FIRST when asking "what module do I reach for", "does Effect have a Sink/Pool/Trie/pattern-matcher", "what is Sink/Channel/Deferred/RcMap for", "where does X live in the source", or before designing ANY capability (the contract-inventory gate greps this map's territory). Opens with a routing-by-task table for the ones people miss by name — spawning a subprocess, a TTL cache with in-flight de-duplication, writing to stdout from a library. Rows route; they do not teach — patterns live in the other effect-v4-* skills, and the source is the authority on signatures and semantics.
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the Effect V4 Module Index skill?
Use Effect V4 Module Index when your Claude Code task falls under the General category — specifically in the legal compliance area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Effect V4 Module Index" or describe the task and let Claude pick). Browse related skills at /category/general/.
What is a Claude Code skill and how does the Effect V4 Module Index skill fit in?
A Claude Code skill is a 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. Effect V4 Module Index 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/.

Attribution & license

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA
spencerbeggs. (2026). Effect V4 Module Index [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/effect-v4-module-index/
BibTeX
@misc{effect-v4-module-index-2026,
  author    = {spencerbeggs},
  title     = {Effect V4 Module Index [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/effect-v4-module-index/}
}

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Security scan

Grade A · scanned 2026-09-28 — free static scan against the OWASP Agentic Skills Top 10.

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