README.md

@putout/plugin-maybe

🐊Putout plugin helps with maybe monad.

Install

npm i @putout/plugin-maybe -D

Rules

• ✅ array;
• ✅ empty-array;
• ✅ fn;
• ✅ noop;
• ✅ declare;

Config

{
    "rules": {
        "maybe/array": "on",
        "maybe/empty-array": "on",
        "maybe/fn": "on",
        "maybe/noop": "on",
        "maybe/declare": "on"
    }
}

array

❌ Example of incorrect code

const {isArray} = Array;
const array = isArray(a) ? a : [a];

✅ Example of correct code

const {isArray} = Array;
const maybeArray = (a) => isArray(a) ? a : [a];
const array = maybeArray(a);

empty-array

❌ Example of incorrect code

const array = !a ? [] : a;

✅ Example of correct code

const maybeArray = (a) => !a ? [] : a;
const array = maybeEmptyArray(a);

fn

❌ Example of incorrect code

const isFn = (a) => typeof a === 'function';
const fn = isFn(a) ? a : () => {};

✅ Example of correct code

const isFn = (a) => typeof a === 'function';
const noop = () => {};
const maybeFn = isFn(a) ? a : noop;
const fn = maybeFn(a);

noop

❌ Example of incorrect code

const fn = f || (() => {});

✅ Example of correct code

const noop = () => {};
const fn = fn || noop;

declare

Declares:

• ✅ maybeArray;
• ✅ maybeEmptyArray;
• ✅ maybeArrayFrom;
• ✅ maybeFn;
• ✅ maybeFirst;
• ✅ maybeCall;

❌ Example of incorrect code

When you not sure is f a function, but you want to use it as function anyways:

const fn = maybeFn(f);

maybeCall(fn);

✅ Example of correct code

const isFn = (a) => typeof a === 'function';
const noop = () => {};
const maybeFn = (a) => isFn(a) ? a : noop;
const maybeCall = (a, ...b) => isFn(a) && a(...b);

const fn = maybeFn(f);
maybeCall(fn);

When you not sure is a is an array or not, but you want to get first element of it.

❌ Example of incorrect code

const b = maybeFirst(a);

✅ Example of correct code

const {isArray} = Array;
const maybeFirst = (a) => isArray(a) ? a[0] : a;

const b = maybeFirst(a);

License

MIT