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.
npx agentmods add skills/mickeyyaya/refactoring-skills/refactor-functional-patternsnpx skills add mickeyyaya/refactoring-skills --skill refactor-functional-patternsgit clone --depth 1 https://github.com/mickeyyaya/refactoring-skillsWrote 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.
[](https://agentmods.dev/skills/mickeyyaya/refactoring-skills/refactor-functional-patterns)<a href="https://agentmods.dev/skills/mickeyyaya/refactoring-skills/refactor-functional-patterns"><img src="https://agentmods.dev/badge/skills/mickeyyaya/refactoring-skills/refactor-functional-patterns.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00056 | $0.02678 |
| Opus 5 | $0.00028 | $0.01339 |
| Sonnet 5 | $0.00011 | $0.00536 |
| Haiku 4.5 | $0.00006 | $0.00268 |
Grade A, and why
refactor-functional-patterns 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 5d ago.
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.
How it starts
The opening of the file, as written. The whole thing — 328 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Refactor: Functional Programming Patterns
Overview
FP patterns produce code that is predictable, testable, and composable by eliminating shared mutable state and side effects.
When to use: State mutation bugs, hidden dependencies, untestable functions, complex data pipelines, repeated null-check boilerplate, functions mixing computation and I/O.
Quick Reference
| Pattern | Core Idea | Primary Red Flag |
|---|---|---|
| Pure Functions | Same input → same output, no side effects | Accessing global state inside business logic |
| Immutability | Never mutate, always create new | push, pop, or property assignment on existing objects |
| Map/Filter/Reduce | Declarative collection transforms | Manual loops accumulating results |
| Function Composition | Build pipelines from small functions | Deeply nested function calls f(g(h(x))) |
| Higher-Order Functions | Functions that take/return functions | Copy-pasted blocks differing by one operation |
| Currying / Partial Application | Fix some arguments, defer the rest | Repeatedly passing the same first argument |
| Functors / Monads | Chainable containers for optional/error values | Nested null checks, try-catch pyramids |
| Pattern Matching | Destructure and branch on data shape | instanceof chains or long type-checking conditionals |
Patterns in Detail
1. Pure Functions
Red Flags: Reading global/process.env in computation; I/O mixed into business logic; parameter mutation (arr.push(x)); Date.now()/Math.random() in deterministic functions.
// BEFORE — reads global state + side effect
let taxRate = 0.2;
function calculateTotal(price: number): number {
const total = price * (1 + taxRate);
console.log(`total: ${total}`);
return total;
}
// AFTER — pure: only uses arguments
function calculateTotal(price: number, taxRate: number): number {
return price * (1 + taxRate);
}
# Python equivalent
def calculate_total(price: float, tax_rate: float) -> float:
return price * (1 + tax_rate)
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.
- 5d ago First seen · 328 lines · 56 tokens per session scan A 104d02a55d42
refactor-functional-patterns is a skill published in the GitHub repository mickeyyaya/refactoring-skills (6 stars, last pushed 5mo ago), licensed MIT. It adds 56 tokens to every session and 2,678 once invoked, about $0.0003 per session on Opus 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.
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