op-lift

turns js operators into delicious first-class functions

op-lift

Turn js operators into delicious first-class functions.

var lift = require('op-lift')
 
;[1, 2, 3, 4].reduce(lift('+')) //= 10 

install via npm: npm install op-lift test: cd node_modules/op-lift && npm test

Requires an es5, or es5-shim for older engines.

lift takes a string representing an operator, and returns a function that performs the same job.

var lift = require('op-lift')
 
;[1, 2, 3, 4].reduce(lift('*')) //= 24 
 
;[true, false, true].map(lift('!')) //= [ false, true, false ] 
;[Object, Array, Function].map(lift('new')).map(lift('typeof')) //= [ 'object', 'object', 'function' ] 

It's safe to use with arbitrary strings, too, since lift will simply return null for unrecognised operators:

 
lift('; console.log(a), a +') //= null 

The supported operators are:

prefix: void typeof ++ -- + - ~ ! new

infix: * / % + - << >> >>> < > <= >= instanceof in == != === !== & ^ | || && . ,

postfix: ()

weirdfix: ?:

Since the resulting functions simply accept values as arguments, no short-circuiting can be done:

lift('||')(false, alert('BOO')) // an alert still shows up with 'BOO' 

Any operator that affects a variables' value won't in its lifted form:

var a = 0
lift('++')(a) // 1 
a             // 0 

Since the primary difference between operators and functions is that functions are first class, op-lift works very well with libraries heavy on the higher-order functions, including:

  • tap - allows functions to be injected into the method chain
  • underscore - uses functional iterators, and has standard functional partial application & composition.