fp-ts Backend Patterns

Functional programming patterns for building type-safe, testable backend services using fp-ts.

Version and execution scope

Pin fp-ts, TypeScript, framework and Prisma versions; these excerpts omit application types/helpers and do not form a compiled package. fp-ts TaskEither represents only errors wrapped by its adapters; thrown exceptions/rejected promises still require handling. Deno needs explicit npm/runtime configuration and Node APIs are not automatically portable. Validate effects and error paths against real adapters before adopting the patterns.

Detailed Guide

Read the detailed guide before executing this skill. It retains the complete procedure and reference material. Treat its safety, prerequisites, and validation requirements as mandatory. For focused work, load the relevant sections; for end-to-end work, read the guide completely.

When to Use

• You are building or refactoring a Node.js or Deno backend with fp-ts.
• The task involves dependency injection, service composition, or typed backend errors with ReaderTaskEither.
• You need functional backend architecture patterns rather than isolated utility snippets.