Month: September 2011

Partial application in Javascript part 3

Here is the last part of the videos on partial application. We improve the code from previous videos and make it handle a variable number of parameters.

In the video, I mention that n is the number of times we will have to apply partial application before the underlying function is called. That is misleading. The situation is actually a little better than that. n is really the number of parameters the underlying function cares about. After n parameters are passed in, the original function will be called. Whether or not we pass in the parameters all at once (a, b, c) or one at a time.

Here is the final code:

 1 <html>
 2     <body>
 3         <scriptlanguage="javascript">
 4 
 5 Function.prototype.partial = function(n){
 6 var original_function = this;
 7 var args = [];
 8 
 9 var recursive_partial = function(){
10                     args = args.concat([].slice.apply(arguments));
11 if(args.length >= n){
12 return original_function.apply(null, args);
13 }
14 return recursive_partial;
15 };
16 return recursive_partial;
17 }
18 
19 function addTwoNumbers(a,b){return a+b;}
20 function addThreeNumbers(a,b,c){return a+b+c;}
21 
22 </script>
23 
24         Partial application #3
25 
26     </body>
27 </html>

Partial application in Javascript part 2

Here is part 2 of the videos on partial application in Javascript. We take the initial prototype and make it handle three parameters.

Here is the code:

 1 <html>
 2     <body>
 3         <scriptlanguage="javascript">
 4 
 5 Function.prototype.partial3 = function(){
 6 var original_function = this;
 7 
 8 var args1 = [].slice.apply(arguments);
 9 returnfunction(){
10 var args2 = [].slice.apply(arguments);
11 returnfunction(){
12 var args3 = [].slice.apply(arguments);
13 return original_function.apply(null, args1.concat(args2).concat(args3));
14 }
15 };
16 };
17 
18 function addThreeNumbers(a,b,c){return a+b+c;}
19 
20 </script>
21 
22         Partial application #2
23 
24     </body>
25 </html>
26

Partial application in Javascript part 1

I recently recorded a few videos on partial application in JavaScript. In part 1, I explain what it is and I provide a short code snippet as a first draft. I will build upon the code snippet in the subsequent videos.

Here is the code that I am using:

<html>
    <body>
        <scriptlanguage="javascript">

Function.prototype.partial = function(){
var original_function = this;
var args1 = [].slice.apply(arguments);

returnfunction(){
var args2 = [].slice.call(arguments);
return original_function.apply(null, args1.concat(args2));
};
};

function addTwoNumbers(a,b){return a+b;}

</script>

        Partial application #1

    </body>
</html>

Getting things done

For a few weeks now I’ve been using some sort of GTD system to manage my todos. The GTD — Getting Things Done — system is simple but I guess it’s got a few  things to it so there’s a book about it.

To me, it boils down to how to manage a bunch of todo lists. I have a handful of todo lists, one for each “project” that I want to get done. And I tag individual todos with labels like @next, @soon, @waiting, or @reference. I try to always write down a todo for everything I want to achieve and I sort it into one of the projects.

When I go into planning mode, I tag lots of todos as @next. A quick search for that label will give me my current consolidated todo list. As I get those todos done, I delete them or remove the label and tag some more… Ring around the rosie.

The GTD workflow is easily understood from the following diagram:

The GTD workflow – copyright David Allen

A lot of software options are available to implement some sort of GTD workflow. But I have settled on the Springpad Android app. It’s got bugs but it’s very powerful and it does everything I need for GTD-style management. Hopefully they’ll sort out the bugs soon enough.

Springpad’s home view

When I am really totally obsessed about getting things done, I sometimes use the Pomodoro technique. This one also has a book but frankly, it probably does not deserve that much literature. It’s too simple: set a timer for 25 minutes and that’s the time you have to get something done. Then take a five-minute break. Rinse and repeat. Everything else is fluff. There is an Android app for that too.