lazy-sequence

Lazy sequences in JavaScript.

It's still in development.

Main purpose is to create lazy sequences acting like arrays.

You can use it in node or in browser using some browser module manager like webpack or browserify.

npm install lazy-sequence

Example of usage:

Recursive sequences

  import lazy from 'lazy-sequence';
 
  let fib = lazy([0, 1], (n) => fib[n - 1] + fib[n - 2]);
 
  0 in fib // true
  3 in fib // false
 
  fib[3]; // 2
 
  3 in fib // true
 
  5 in fib // false
 
  fib[9]; // 34
 
  5 in fib // true

Simplest usage

  import lazy from 'lazy-sequence';
 
  let even = lazy(n => 2 * n);
 
  even[0] // 0
  even[1] // 2
  even[3] // 6
  // ....

You can set length limit

  import lazy from 'lazy-sequence';
 
  let limited = lazy({array: [0, 1], length: 50}, (n) => limited[n - 1] + limited[n - 2]);
 
  limited.length; // 50
 
  limited[9] // 34
 
  49 in limited // false
 
  // you can test if index is in range of length
 
  limited.inRange(49) // true
 
  limited.inRange(70) // false
 
  limited.fillAll();
 
  49 in limited // true
 
  // you can exceed the limit - it will behave like simple array
 
  limited[70] // 190392490709135

You can convert it into real array

  import lazy from 'lazy-sequence';
 
  let even = lazy(n => 2 * n);
 
  even[0] // 0
  even[1] // 2
  even[3] // 6
 
  even.toArray(); // [0, 2, ,6]

It relies on Proxy - make sure Proxy is a present - native or some standard pollyfill!

But also it's transpiled with babel for backward compatibility.

DOCs and test will come soon.