fp-pack

fp-pack is a practical functional programming toolkit designed for JavaScript and TypeScript developers who want composition-first APIs without complex monads or wrapper ceremonies. It centers on pipe and pipeAsync for clean, left-to-right function composition, with strong TypeScript type inference that works without manual annotations. The library includes a SideEffect pattern for declarative error handling and early exits, lazy stream processing for memory-efficient operations on large datasets, and curried utilities for point-free style composition. Zero dependencies and tree-shakeable, fp-pack scales from simple scripts to larger codebases while maintaining readable, maintainable code.

["Identify the imperative code you want to refactor. Look for chains of operations (map/filter/reduce) or nested function calls.","Replace imperative chains with fp-pack's `pipe` function. Start by importing `pipe` and the necessary utilities (map, filter, etc.).","Convert side effects to pure functions using fp-pack's `IO` or `Task` types. Wrap impure operations (like API calls) in these types.","Add JSDoc comments to each step in the pipeline to document transformations. Use type annotations to ensure type safety.","Test the transformed code thoroughly. fp-pack's type safety should catch many potential errors during compilation.","Tip: Use fp-pack's currying utilities to create reusable transformation steps. For example, `map(trim('name'))` is more reusable than `map(u => ({ ...u, name: u.name.trim() }))`."]