fp-ts Option and Either
fp-ts Option and Either Guide
This skill covers practical usage of Option and Either from fp-ts for safer TypeScript code.
When to Use Option vs Either
Use Option when:
- A value may or may not exist (nullable/undefined scenarios)
- You don't need to know WHY a value is missing
- Working with optional fields, array lookups, or dictionary access
Use Either when:
- An operation can fail and you need error information
- Replacing try-catch blocks
- You need to communicate different failure reasons
- Building validation pipelines
Imports
More from whatiskadudoing/fp-ts-skills
functional programming fundamentals
Core FP concepts including pure functions, currying, composition, and pointfree style - the foundation for mastering functional TypeScript
81fp-ts-backend
Functional programming patterns for Node.js/Deno backend development using fp-ts, ReaderTaskEither, and functional dependency injection
52pragmatic functional programming
A practical, jargon-free guide to functional programming - the 80/20 approach that gets results without the academic overhead
40functional programming in react
Practical patterns for using fp-ts with React - hooks, state, forms, data fetching. Works with React 18/19, Next.js 14/15.
40fp-immutable
Practical immutability patterns in TypeScript - spread operators, nested updates, readonly types, and when mutation is actually fine
39fp-ts-validation
Validation patterns using fp-ts with error accumulation, form validation, and API input validation
39