JavaScript Named Curry

named-curry.js

function namedCurry(source_fn, arg_order){

  function receiver( received_values, n_received, defaults ){
    received_values = (received_values || []).slice()
    n_received = n_received || 0

    Object.keys(defaults).forEach(function( input_arg ){
      var value = defaults[ input_arg ]
      var required_index = arg_order.indexOf( input_arg )
      var is_known_argument = required_index > -1
      var existing_value = received_values[required_index]

      if( is_known_argument ){
        if( typeof existing_value == "undefined" ){
          n_received++
        }
        received_values[required_index] = value;
      }

    })

    if( n_received >= arg_order.length ){
      return source_fn.apply(null, received_values )
    } else {
      return receiver.bind( null, received_values, n_received )
    }
  }

  return receiver.bind(null, null, 0)
}



// Example usage
// The original render function with positional arguments.
function render(controller, view, renderImmediately ){
  console.log("Rendering",view,"as part of a",controller,"controller", renderImmediately ? "(now)" : "(later)" )
}

// A curried-options object style version of the original render function.
// Notice the argument names are different to the source code.
var namedRender = namedCurry(render, ["ctrl", "view", "immediate"])


//Creating some preconfigured functions for different areas of the site.

//This function is waiting on the `immediate` parameter before being invoked.
var modal_signup = namedRender({
  ctrl: "modal",
  view: "signup form"
})

//This function is waiting for the `view` parameter before being invoked.
var sidebar_later = namedRender({
  ctrl: "sidebar",
  immediate: false
})

//Invoking the signup modal _immediately_
modal_signup({
  immediate: true
})

//Invoking the signup modal _later_
modal_signup({
  immediate: false
})

//Invoking the sidebar with some navigation icons _later_
sidebar_later({
  view: "naviagation-icons"
})

//Invoking the sidebar_later as above, but we are overwriting the immediate property at call time.
sidebar_later({
  immediate: true,  //you can overwrite existing properties
  view: "naviagation-icons"
})