Asca

Convenient and readability improving parameter binding for asynchronous JavaScript functions.

1. load it

   asca = require 'asca'

2. define asynchronous functions using asca

   sayHi = asca (name, done) ->
     console.log "Hello #{name}"
     done()

3. the sayHi method behaves completely normal if called normally, i.e. given all parameters

   sayHi 'world', ->   #> "Hello world" & calls the given method when done

4. if called without the last parameter (the asynchronous callback), the sayHi method returns a method with all the given parameters bound to it. This method can be called later by just giving it the callback.

   sayWorldLater = sayHi 'world'   # 'sayWorldLater' is the sayHi method with
                                   # the argument 'world' bound to it
   sayWorldLater ->                #> "Hello world" & calls the given method when done

5. This binding allows very readable asynchronous code constructs, for example when using async.js:

   # instead of this madness
   async.parallel [
     (done) -> sayHi 'world', done
     (done) -> sayHi 'universe', done
   ]
   
   # or this mess
   async.parallel [
     sayHi.bind this, 'world'
     sayHi.bind this, 'universe'
   ]
   
   # we can now say
   async.parallel [
     sayHi 'world'
     sayHi 'universe'
   ]

   Or in many other places that call a method later

   # instead of
   setTimeout (-> sayHi 'world'), 2000
   
   # we can now say
   setTimeout sayHi('world'), 2000

   All asynchronous JavaScript methods should behave like this.

   There are other libraries like curry that provide more comprehensive currying and binding, and might be more appropriate depending on what you want to do. This library is focussed around delayed asynchrounous function calling, performs error checking specifically for this use case, and does that with high performance while being extremely lightweight.