Fp option ref

Skill sickn33/agentic-awesome-skills/plugins/agentic-awesome-skills-claude/skills/fp-option-ref

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Install

npx -y skills add sickn33/agentic-awesome-skills --skill fp-option-ref

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What its author says it does

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Quick reference for Option type. Use when user needs to handle nullable values, optional data, or wants to avoid null checks.

SKILL.md

2.3 KB, 521 tokens by cl100k_base, as published. Nobody here has run it

Option Quick Reference

Option = value that might not exist. Some(value) or None.

When to Use

You need a quick fp-ts reference for nullable or optional values.
The task involves eliminating null checks, safe property access, or optional chaining with Option.
You want a short reference card rather than a full migration guide.

Create

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)

Transform

O.map(fn)              // Transform inner value
O.flatMap(fn)          // Chain Options (fn returns Option)
O.filter(predicate)    // None if predicate false

Extract

O.getOrElse(() => default)  // Get value or default
O.toNullable(opt)           // Back to T | null
O.toUndefined(opt)          // Back to T | undefined
O.match(onNone, onSome)     // Pattern match

Common Patterns

import { pipe } from 'fp-ts/function'
import * as O from 'fp-ts/Option'

// Safe property access
pipe(
  O.fromNullable(user),
  O.map(u => u.profile),
  O.flatMap(p => O.fromNullable(p.avatar)),
  O.getOrElse(() => '/default-avatar.png')
)

// Array first element
import * as A from 'fp-ts/Array'
pipe(
  users,
  A.head,  // Option<User>
  O.map(u => u.name),
  O.getOrElse(() => 'No users')
)

vs Nullable

// ❌ Nullable - easy to forget checks
const name = user?.profile?.name ?? 'Guest'

// ✅ Option - explicit, composable
pipe(
  O.fromNullable(user),
  O.flatMap(u => O.fromNullable(u.profile)),
  O.map(p => p.name),
  O.getOrElse(() => 'Guest')
)

Use Option when you need to chain operations on optional values.

Limitations

Use this skill only when the task clearly matches the scope described above.
Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.