What is functional-core-imperative-shell?

A refactoring guide for separating business decisions from outside effects in TypeScript code. Outside effects include database access, input and output, changing state, time, and random values.

Use it when extracting pure business logic, separating rules from databases, or splitting code into a functional core and a thin imperative shell.

Separating these parts makes the decision-making code easier to test without replacing real services with mock versions.

functional-core-imperative-shell — Skill by noel-yap/dot-ai

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add noel-yap/dot-ai --skill functional-core-imperative-shell

Clone the repo

git clone --depth 1 https://github.com/noel-yap/dot-ai

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/noel-yap/dot-ai/functional-core-imperative-shell/github.svg)](https://agentmods.dev/skills/noel-yap/dot-ai/functional-core-imperative-shell)

Your own site

<a href="https://agentmods.dev/skills/noel-yap/dot-ai/functional-core-imperative-shell"><img src="https://agentmods.dev/badge/skills/noel-yap/dot-ai/functional-core-imperative-shell/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/noel-yap/dot-ai/functional-core-imperative-shell"><img src="https://agentmods.dev/badge/skills/noel-yap/dot-ai/functional-core-imperative-shell.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 98 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,106 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin unknown No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00098	$0.03106
Opus 5.5	$0.00039	$0.01242
Sonnet 5.5	$0.00020	$0.00621
Haiku 4.5	$0.00010	$0.00311

Measured 2mo ago against content hash e04e0bf70baa, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

functional-core-imperative-shell scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

The scan reads SKILL.md. This mod also ships 7 executable files (evals/_assertions.py, evals/conftest.py, evals/samples/order_processor.ts, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/functional-core-imperative-shell/SKILL.md · 318 lines

The source is not reproduced here

No licence file

Read it on GitHub

Files

What ships with it

9 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 318 lines · 98 tokens per session scan A e04e0bf70baa

Subscribe to this mod's changes

functional-core-imperative-shell is a skill published in the GitHub repository noel-yap/dot-ai (2 stars, last pushed 3mo ago), with no licence file. It adds 98 tokens to every session and 3,106 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Code review Languages TypeScript

functional-core-imperative-shell next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
functional-core-imperative-shellnoel-yap/dot-ai	Skill	2	3mo ago	none	A	98	Claude Code, Codex
no-bare-castsprisma/orm	Skill	48k	today	Apache-2.0	A	52	Claude Code, Codex
coding-standardshashgraph-online/awesome-codex-plugins	Skill	1.5k	today	Apache-2.0	A	28	Claude Code, Codex
best-practicesFradSer/dotclaude	Skill	596	yesterday	MIT	A	52	Claude Code
plankton-code-qualityloulanyue/awesome-claude-notes	Skill	271	1mo ago	MIT	A	34	Claude Code
architecture-auditorg2AI/ORG2	Skill	2.6k	3d ago	AGPL-3.0	A	70	Claude Code, Codex
supermux-coreUstaLabs/supermux	Skill	31	yesterday	MIT	A	46	Claude Code, Codex