edtsech / polyfun

Extendable polymorphic funcitons [EXPERIMENTAL]

Polyfun

Polyfun allows you to write functions which supports single dispatch on type. It means you can write polymorphic functions or extend third-party functions for specific types.

Define function without any implementation:

var f = fun()

Add support for specific type:

f.define(Number, function() {
  return 'number'
})

f(12) // => 'number'

f("12") // => throw new TypeError("Type is not supported")

Type dispatching works on:

• null
• undefined
• native types
• custom types

How to check if type is supported by particular "poly" function?

f.supportedTypes() // => {Number: fun...}
f.isSupported(String)

Define function with default implementation:

var indentity = fun(function(val) {
  return val;
})

identity(1) // => 1

How to check if 'poly' function has a default implementation?

f.hasDefault()