A lightweight markup language is a markup language with a simple syntax, designed to be easy for a human to enter with a simple text editor, and easy to read in its raw form....
XHTML is a family of XML markup languages that mirror or extend versions of the widely-used Hypertext Markup Language , the language in which web pages are written....
A web document is similar in concept to a web page, but also satisfies the following broader definition:The term "web document" has been used as a fuzzy term in many sources A web document is similar in concept to a web page, but also satisfies the following broader (W3C) definition:The term "web...
without the use of traditional inline coding. It’s designed to address many of the flaws in traditional templating engines, as well as making markup as elegant as it can be. Haml functions as a replacement for inline page templating systems such as PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
Active Server Pages , also known as Classic ASP or ASP Classic, was Microsoft's first server-side script engine for dynamically-generated Web pages. Initially released as an add-on to Internet Information Services via the Windows NT 4.0 Option Pack Active Server Pages (ASP), also known as Classic...
. However, Haml avoids the need for explicitly coding XHTML into the template, because it is itself a description of the XHTML, with some code to generate dynamic content.
-Computing:*Cascading Style Sheets, a language used to describe the style of document presentations in web development*Central Structure Store in the PHIGS 3D API*Closed source software, software that is not distributed with source code...
is Sass.
Principles
Markup should be beautiful
Markup should not be used merely as a tool to get browsers to render a page the way its author wants it rendered. The rendering isn't the only thing people have to see; they have to see, modify, and understand the markup as well. Thus, the markup should be just as user-friendly and pleasant as the rendered result.
Dry or dryness may refer to:* Lack of water* Prohibiting alcohol * Dryness , the lack of sugar in a drink, especially an alcoholic one * Dryness * Dryness...
XHTML involves major repetition. Most elements have to be named twice: once before its content and once after. ERB
ERuby
eRuby is a templating system that embeds Ruby into a text document. It is often used to embed Ruby code in an HTML document, similar to ASP, JSP and PHP.-Usage:eRuby allows Ruby code to be embedded within a pair of delimiters...
adds even more repetition and unnecessary characters. Haml avoids all of this by relying on indentation, not text, to determine where elements and blocks of code begin and end. Not only does this result in smaller templates, it makes the code much cleaner to look at.
Markup should be well-indented
One of the major problems with traditional templating languages is that not only do they not encourage well-indented code, they actively make it challenging, or even impossible, to write. The result is confusing, unreadable XHTML. Haml formats tags so they are well indented and reflect the underlying structure of the document.
XHTML structure should be clear
XML and XHTML are formats built upon the idea of a structured document. That structure is reflected in their markup, and it should likewise be reflected in meta-markup such as Haml. Because Haml's logic is based on indentation of child elements, this structure is naturally preserved, making the document much easier and more logical for mere humans to read.
Example
Note: This is a simple preview example and may not reflect the current version of the language.
The official implementation of Haml has been built for Ruby
Ruby (programming language)
Ruby is a dynamic, reflective, general-purpose object-oriented programming language that combines syntax inspired by Perl with Smalltalk-like features. Ruby originated in Japan during the mid-1990s and was first developed and designed by Yukihiro "Matz" Matsumoto...
Merb, short for "Mongrel+Erb", is a model–view–controller web framework written in Ruby. Merb adopts an approach that focuses on essential core functionality, leaving most functionality to plugins. Merb was merged into Rails web framework on December 23, 2008 as part of the Ruby on Rails 3.0...
, but the Ruby implementation also functions independently.
There are also implementations in other languages:
Haml was invented in May 2006 by Hampton Catlin. However, Nathan Weizenbaum is responsible for the maturation of the Haml codebase. At this time, Haml is considered a highly stable language.
BBCode or Bulletin Board Code is a lightweight markup language used to format posts in many message boards. The available tags are usually indicated by square brackets surrounding a keyword, and they are parsed by the message board system before being translated into a markup language that web...
eRuby is a templating system that embeds Ruby into a text document. It is often used to embed Ruby code in an HTML document, similar to ASP, JSP and PHP.-Usage:eRuby allows Ruby code to be embedded within a pair of delimiters...
Markaby is a small Ruby library for writing HTML code in pure Ruby. It is an alternative to templating languages such as ERb and HAML which combine Ruby code with some form of markup...
Ruby is a dynamic, reflective, general-purpose object-oriented programming language that combines syntax inspired by Perl with Smalltalk-like features. Ruby originated in Japan during the mid-1990s and was first developed and designed by Yukihiro "Matz" Matsumoto...
A web template is a tool used to separate content from presentation in web design, and for mass-production of web documents. It is a basic component of a web template system.Web templates can be used to set up any type of website...
YAML is a human-readable data serialization format that takes concepts from programming languages such as C, Perl, and Python, and ideas from XML and the data format of electronic mail . YAML was first proposed by Clark Evans in 2001, who designed it together with Ingy döt Net and Oren Ben-Kiki...
SASS - A similar system for CSS, also designed by Catlin.
