Generate fp-ts Option type code snippets

Option Quick Reference is a compact fp-ts cheat sheet for the Option type, defined in the skill as a value that might not exist: either Some(value) or None. It is a short reference card rather than a full migration guide, meant for handling nullable or optional data without scattered null checks.

The reference is organized in four blocks. Create shows how to build Options: O.some(5), O.none, O.fromNullable(x) which turns null or undefined into None, and O.fromPredicate which yields None when the predicate is false. Transform covers O.map for the inner value, O.flatMap for chaining functions that return an Option, and O.filter which gives None when the predicate fails. Extract covers O.getOrElse for a default, O.toNullable and O.toUndefined for going back to T or null and T or undefined, and O.match with onNone and onSome handlers.

A Common Patterns section shows safe property access with pipe, chaining fromNullable, map, flatMap and getOrElse to reach a user's avatar with a default image path, and taking the first element of an array with A.head from fp-ts/Array. A comparison against plain nullable code shows that optional chaining is easy to forget checks in, while the Option version is explicit and composable. The stated rule of thumb is to use Option when you need to chain operations on optional values.

Use it when you need a quick fp-ts reference for nullable or optional values, when the task involves eliminating null checks, safe property access or optional chaining with Option, or when you want a short reference card instead of a full migration guide.

It is not a tutorial or migration guide. The skill's limitations say to use it only when the task clearly matches its scope, not to treat output as a substitute for environment-specific validation, testing or expert review, and to ask for clarification if inputs or success criteria are missing.

The input is a piece of TypeScript code that handles nullable values, or a question about which Option function to use. The output is the matching fp-ts snippet. The creation snippet is representative:

import * as O from 'fp-ts/Option'
O.some(5)              // Some(5)
O.none                 // None
O.fromNullable(x)      // null/undefined → None, else Some(x)
O.fromPredicate(x > 0)(x) // false → None, true → Some(x)

The skill is written for TypeScript projects that use the fp-ts library. It imports Option from fp-ts/Option, pipe from fp-ts/function and Array helpers from fp-ts/Array. It is tagged fp-ts, option, nullable, maybe and quick-reference.

It is for TypeScript developers using or adopting fp-ts who want fast lookups of Option constructors, transformers and extractors, and a clear example of when Option beats optional chaining.