lazy-o

Painless chains that are lazy, functional, and fast.

var lazy = require('lazy-o')
 
var foo = lazy
  ('map', x => x + 3) // Queue a call
  ('slice', 3, 5) // Queue more calls
  (console.log) // Use plain function
 
// Apply calls on a value with '.run'
foo.run([1, 2, 3, 4, 5, 6])
// => [ 7, 8 ]

A small utility for creating execution chains that are functional.

Note: If you are creating JS APIs with this, you want to only expose .run to the user. So they can call it like a normal function (foo() vs foo.run()), and also to prevent them putting extra calls on the lazy stack.

Installation

$ npm install --save lazy-o

API

lazy(method, [...args])

Queue a method to run on the value.

• name (String|Token): The operation you want to queue.
• args: Arguments to supply to the method during execution.

Returns self, so you can chain more methods.

var foo = lazy
  ('map', x => x + 1)
  ('slice', 1).run
 
foo([1, 2, 3])
// => [3, 4]

lazy(fn)

Queue a plain function to run, the return replaces value.

• fn (Function): A function that is run with the value

Returns self, so you can chain more methods.

var foo = lazy(x => x + 1).run
 
foo(10)
// => 11

lazy.run(value)

lazy.run(...values)

Run all the queued calls on value or values.

Returns the resulting a modified value or array of values after all the calls have been applied.

Example with a single value:

var foo = lazy('map', x => x + (x > 4 ? 1 : -1)).run
 
foo([1, 2, 3, 4, 5, 6, 7, 8])
// => [0, 1, 2, 3, 6, 7, 8, 9]

Multiple values:

var bar = lazy('slice', 1, -1)('toUpperCase').run
 
bar.run('foobar', 'bazqux', 'hello world')
// => ['OOBA', 'AZQU', 'ELLO WORL']

Meta

• npm test: Run tests.
• npm run bench: Run benchmarks.

License

MIT © Jamen Marz