nyinyithann/xpando

Xpando extends JavaScript Array, Map, and Set.

Xpando.js

A library that extends JavaScript Array, Map, and Set.

Xpando is a JavaScript library for nodeJS and browser. Xpando extends JavaScript Array, Map, and Set. The library is heavily inspired and influenced by F# Array, Map, and Set modules.

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Please note **xpando npm package** is deprecated. The following three separated packages are introduced instead.
[Vec.js] (https://www.npmjs.com/package/@nyinyithann/vec.js)
[Dict.js] (https://www.npmjs.com/package/@nyinyithann/dict.js)
[Uniq.js] (https://www.npmjs.com/package/@nyinyithann/uniq.js)

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Installation

npm install xpando

Getting started

Xpando has three major types Vec (Vector), Dict (Dictionary), Uniq (Unique) and their methods. Vec extends Array. Dict extends Map. Uniq extends Set.

Vec

Vec extends Array. All built-in methods of Array can be used with it. The following snippet demonstrates using Array's built-in method reduce with Vec.

const fnVec = Vec.of(x => x * x * x, x => x / 216, Math.sqrt);
const howLongAStormLast = d => fnVec.reduce((s, f) => f(s), d);
console.log(howLongAStormLast(10.5)); // => 2.315032397181517

Vec comes with additional 50+ methods. The following snippets demonstrate some of them.

// unfold
const fibonacci = (n) => Vec.unfold(([x, [a, b]]) => (x < n ? [a + b, [x + 1, [b, a + b]]] : null), [0, [0, 1]]);
const fibOf10 = fibonacci(10);
console.log(fibOf10);
// => [ 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 ]

// mapFold
const oneToTen = Vec.init(10, x => x + 1);
const mapFoldResult = oneToTen.mapFold((acc, elem) => [acc, acc + elem], 0);
console.log(mapFoldResult);
// => [ [ 0, 1, 3, 6, 10, 15, 21, 28, 36, 45 ], 55 ]

// scan
const scannedResult = oneToTen.scan((acc, elem) => acc + elem, 0);
console.log(scannedResult);
// => [ 0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55 ]

// groups
const groups = oneToTen.groupBy( x => x % 2 === 0 ? 'Even' : 'Odd', true);
console.log(groups);
// => [ [ 'Odd', [ 1, 3, 5, 7, 9 ] ], [ 'Even', [ 2, 4, 6, 8, 10 ] ] ]

Vec can be instantiated as follows:

const vec = new Vec();
vec.push(1, 2, 3, 4, 5);
// => [ 1, 2, 3, 4, 5 ]

const vec1 = new Vec(1, 2, 3, 4, 5); 
// => [ 1, 2, 3, 4, 5 ]

const vec2 = Vec.of(1, 2, 3, 4, 5); 
// => [ 1, 2, 3, 4, 5 ]

const vec3 = Vec.from([1, 2, 3, 4, 5]); 
// => [ 1, 2, 3, 4, 5 ]

const vec4 = Vec.init(5, x => x + 1); 
// => [ 1, 2, 3, 4, 5 ] 

const vec5 = Vec.unfold(x => x <= 5 ? [x, x + 1] : undefined, 1); 
// => [ 1, 2, 3, 4, 5 ]

const vec6 = Vec.create(5, 1); 
// => [ 1, 1, 1, 1, 1 ]

const emptyVec = Vec.empty();
emptyVec.push(1, 2, 3, 4, 5); 
// => [ 1, 2, 3, 4, 5 ]

Please go to Vec APIs to read more about Vec APIs.

Dict

Dict extends Map. All built-in methods of Map can be used with Dict. And Xpando provides additional methods.

const diatonicMajorInC = new Dict(
  [
    [1, ['C', 'do']],
    [2, ['D', 're']],
    [3, ['E', 'mi']],
    [4, ['F', 'fa']],
    [5, ['G', 'so']],
    [6, ['A', 'la']],
    [7, ['B', 'ti']]
  ]
);
const twinkelLittleStarNotes = new Vec(1, 1, 5, 5, 6, 6, 5);
const solfeges = diatonicMajorInC.fold((s, k, [_, solfege]) => twinkelLittleStarNotes.includes(k) ? `${s}${solfege} ` : s, '');
console.log(solfeges)
// => do so la

Please go to Dict APIs to read more about Dict APIs.

Uniq

Uniq extends Set. All built-in methods of Set can be used with Uniq. And Xpando provides additional methods.

const somePrimes = new Uniq([2, 3, 5, 7, 11, 13]);
const someEvens = new Uniq([2, 4, 6, 8, 10]);
const evenPrime = somePrimes.intersect(someEvens);
console.log(evenPrime);
// => [Uniq] { 2 }

Please go to Uniq APIs to read more about Uniq APIs.

Author

Nyi Nyi Than - @nyinyithann

Credit

• F# Collections
• Exploring ES6 By Dr. Axel Rauschmayer
• Understanding ECMAScript 6 By Nicholas C. Zakas
• Collection Pipeline by Martin Fowler
• javascript.info

License

MIT