<pedrocorreia.net ⁄>
 

<Haskell Zippers ⁄ >




clicks: 2521 2521 2010-11-14 2010-11-14 goto programacao myNews programacao  Bookmark This Bookmark This


While Haskell's purity comes with a whole bunch of benefits, it makes us tackle some problems differently than we would in impure languages. Because of referential transparency, one value is as good as another in Haskell if it represents the same thing.

So if we have a tree full of fives (high-fives, maybe?) and we want to change one of them into a six, we have to have some way of knowing exactly which five in our tree we want to change. We have to know where it is in our tree. In impure languages, we could just note where in our memory the five is located and change that. But in Haskell, one five is as good as another, so we can't discriminate based on where in our memory they are. We also can't really change anything; when we say that we change a tree, we actually mean that we take a tree and return a new one that's similar to the original tree, but slightly different.



este é só um excerto do artigo, para aceder ao artigo completo, clique no link em baixo:
this is just a small excerpt from the article, to access the full article please click in the link below:

http://learnyouahaskell.com/zippers




Subscribe News RSS  Subscribe News Updates by E-mail





myNews <myNews show="rand" cat="programacao" ⁄>

RouterJs: easy routing for your ajax Web applications new ...

RouterJs is a simple router for your ajax web apps. It's build upon History.js which means that Rout (...)

clicks: 16082 16082 2012-05-14 2012-05-14 goto url (new window) haithembelhaj.g... goto myNews programacao


Backbone computed properties new ...

This gist shows one way to implement read- and write-enabled computed properties on a Backbone Model (...)

clicks: 15912 15912 2012-05-13 2012-05-13 goto url (new window) https://gist.gi... goto myNews programacao


Android Query new ...

Android-Query (AQuery) is a light-weight library for doing asynchronous tasks and manipulating UI el (...)

clicks: 16144 16144 2012-05-12 2012-05-12 goto url (new window) code.google.com... goto myNews programacao


Create Instagram Filters With PHP new ...

In this tutorial, I'll demonstrate how to create vintage (just like Instagram does) photos with PHP (...)

clicks: 15587 15587 2012-05-12 2012-05-12 goto url (new window) net.tutsplus.co... goto myNews programacao


HTML5 jQuery Paint Plugin new ...

Websanova Paint is a HTML5 canvas based jQuery plugin. It allows you to free paint on a canvas area (...)

clicks: 26670 26670 2012-05-12 2012-05-12 goto url (new window) websanova.com/t... goto myNews programacao


Sass vs. LESS vs. Stylus: Preprocessor Shootout new ...

CSS3 preprocessors are languages written for the sole purpose of adding cool, inventive features to (...)

clicks: 15306 15306 2012-05-11 2012-05-11 goto url (new window) net.tutsplus.co... goto myNews programacao


Real-time Applications With Node.js and Socket.IO new ...

Hey everyone! Sorry about the long pause since the last blog post, life has been quite hectic for th (...)

clicks: 15985 15985 2012-05-11 2012-05-11 goto url (new window) codingcookies.c... goto myNews programacao


15 Handpicked jQuery Drop Down Menus Tutorials new ...

Here we are presenting another brilliant collection of 15 jQuery navigation menu that you can downlo (...)

clicks: 15103 15103 2012-05-10 2012-05-10 goto url (new window) smashingapps.co... goto myNews programacao