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.
git clone --depth 1 https://github.com/PaulJPhilp/EffectPatternsWrote 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/rules/pauljphilp/effectpatterns/avoid-long-chains-of-andthen-use-generators-instead)<a href="https://agentmods.dev/rules/pauljphilp/effectpatterns/avoid-long-chains-of-andthen-use-generators-instead"><img src="https://agentmods.dev/badge/rules/pauljphilp/effectpatterns/avoid-long-chains-of-andthen-use-generators-instead.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 | $0.00290 | $0.00290 |
| Opus 5 | $0.00145 | $0.00145 |
| Sonnet 5 | $0.00058 | $0.00058 |
| Haiku 4.5 | $0.00029 | $0.00029 |
Grade A, and why
avoid-long-chains-of-andthen-use-generators-instead 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 8d 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.
What it actually says
description: Prefer generators over long chains of .andThen. globs: "**/*.ts" alwaysApply: true
Avoid Long Chains of .andThen; Use Generators Instead
Rule: Prefer generators over long chains of .andThen.
Example
import { Effect } from "effect";
// Define our steps with logging
const step1 = (): Effect.Effect<number> =>
Effect.succeed(42).pipe(Effect.tap((n) => Effect.log(`Step 1: ${n}`)));
const step2 = (a: number): Effect.Effect<string> =>
Effect.succeed(`Result: ${a * 2}`).pipe(
Effect.tap((s) => Effect.log(`Step 2: ${s}`))
);
// Using Effect.gen for better readability
const program = Effect.gen(function* () {
const a = yield* step1();
const b = yield* step2(a);
return b;
});
// Run the program
const programWithLogging = Effect.gen(function* () {
const result = yield* program;
yield* Effect.log(`Final result: ${result}`);
return result;
});
Effect.runPromise(programWithLogging);
Explanation:
Generators keep sequential logic readable and easy to maintain.
Explanation:
Effect.gen provides a flat, linear code structure that is easier to read and
debug than deeply nested functional chains.
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.
- 8d ago First seen · 44 lines · 290 tokens per session scan A 7c25904e804b
avoid-long-chains-of-andthen-use-generators-instead is a cursor rule published in the GitHub repository PaulJPhilp/EffectPatterns (796 stars, last pushed 2mo ago), licensed MIT. It adds 290 tokens to every session, about $0.0014 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 2026-08-30.
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