fp-pipeline-refactor

name	fp-pipeline-refactor
description	Refactor imperative TypeScript to Effect-first pipeline composition using curried data-first/data-last APIs, Effect collections, and schema-based IO boundaries.

FP Pipeline Refactor

Use this skill when code needs to move from imperative style to Effect + kitz functional composition.

Goals

• Prefer pipeline-friendly composition over statement-by-statement mutation.
• Use Effect-native data structures:
  • HashMap / HashSet
  • mutable variants only when profiling proves they are needed.
• Remove untyped boundaries:
  • avoid JSON.parse
  • avoid try/catch
  • avoid Promise orchestration
  • avoid any and type assertions
• Bridge untyped IO with Schema decode/encode at boundaries.

Repeatable Refactor Flow

1. Identify imperative hotspots.
2. Normalize data flow into pure transforms and Effect.gen orchestration.
3. Replace native Map/Set with Effect HashMap/HashSet where the module is already in Effect context.
4. Replace JSON.parse with Schema.decodeUnknown* and explicit schema models.
5. Replace try/catch with Effect.try, Effect.tryPromise, Either, Option, and typed error channels.
6. Replace promise chains with Effect combinators (Effect.all, Effect.forEach, Effect.promise, Effect.async).
7. Remove any and assertions (as, <T>) by introducing schema/constructor functions at boundaries.
8. Run lint/tests and keep behavior stable.

Refactor Prompt Template

Refactor this module to Effect-first functional composition.

Constraints:

- Use pipeline-friendly, curried composition patterns.
- Prefer Effect data structures (`HashMap`/`HashSet`; mutable variants only if necessary).
- No `JSON.parse` (use Effect Schema decode/encode codecs).
- No `try/catch` (use `Effect.try`, `Either`, `Option`, typed errors).
- No Promise orchestration (use Effect combinators only).
- No `any`, no assertion casts; rely on inference + schema at IO boundaries.

Deliverables:

1. Updated implementation.
2. Updated tests proving behavior unchanged.
3. Short notes listing removed anti-patterns and replacement patterns.