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Haml Changelog

  • Table of contents {:toc}


  • Fixed a bug where Haml's text was concatenated to the wrong buffer under certain circumstances. This was mostly an issue under Rails when using methods like capture.

  • Fixed a bug where template text was escaped when there was interpolation in a line and the :escape_html option was enabled. For example:

    Foo &lt; Bar #{"<"} Baz

    with :escape_html used to render as

    Foo &amp;lt; Bar &lt; Baz

    but now renders as

    Foo &lt; Bar &lt; Baz

Rails XSS Protection

Haml 2.2.9 supports the XSS protection in Rails versions 2.3.5+. There are several components to this:

  • If XSS protection is enabled, Haml's { :escape_html} option is set to true by default.

  • Strings declared as HTML safe won't be escaped by Haml, including the {file:Haml/Helpers.html#html_escape-instance_method #html_escape} helper and &= if :escape_html has been disabled.

  • Haml helpers that generate HTML are marked as HTML safe, and will escape their input if it's not HTML safe.


  • Fixed a potential XSS issue with HTML escaping and wacky Unicode nonsense. This is the same as the issue fixed in Rails a bit ago.


  • Fixed an html2haml issue where ERB attribute values weren't HTML-unescaped before being transformed into Haml.

  • Fixed an html2haml issue where #{} wasn't escaped before being transformed into Haml.

  • Add <code> to the list of tags that's { automatically whitespace-preserved}.

  • Fixed a bug with end being followed by code in silent scripts - it no longer throws an error when it's nested beneath tags.

  • Fixed a bug with inner whitespace-nuking and conditionals. The else et al. clauses of conditionals are now properly whitespace-nuked.


  • Made the error message when unable to load a dependency for html2haml respect the --trace option.

  • Don't crash when the __FILE__ constant of a Ruby file is a relative path, as apparently happens sometimes in TextMate (thanks to Karl Varga).

  • Add "Sass" to the --version string for the executables.

  • Raise an exception when commas are omitted in static attributes (e.g. %p{:foo => "bar" :baz => "bang"}).


  • Got rid of trailing whitespace produced when opening a conditional comment (thanks to Norman Clarke).

  • Fixed CSS id concatenation when a numeric id is given as an attribute. (thanks to Norman Clarke).

  • Fixed a couple bugs with using "-end" in strings.


  • Allow end to be used for silent script when it's followed by code. For example:

    - form_for do
    - end if @show_form

    This isn't very good style, but we're supporting it for consistency's sake.

  • Don't add require 'rubygems' to the top of init.rb when installed via haml --rails. This isn't necessary, and actually gets clobbered as soon as haml/template is loaded.


Haml 2.2.3 adds support for the JRuby bundling tools for Google AppEngine, thanks to Jan Ulbrich.


Haml 2.2.2 is a minor bugfix release, with several notable changes. First, {file:Haml/Helpers.html#haml_concat-instance_method haml_concat} will now raise an error when used with =. This has always been incorrect behavior, and in fact has never actually worked. The only difference is that now it will fail loudly. Second, Ruby 1.9 is now more fully supported, especially with the { new attribute syntax}. Third, filters are no longer escaped when the { :escape_html option} is enabled and #{} interpolation is used.


Haml 2.2.1 is a minor bug-fix release.


Haml 2.2 adds several new features to the language, fixes several bugs, and dramatically improves performance (particularly when running with { :ugly} enabled).

Syntax Changes

HTML-Style Attribute Syntax

Haml 2.2 introduces a new syntax for attributes based on the HTML syntax. For example:

%a(href="" title="Haml's so cool!")
  %img(src="/images/haml.png" alt="Haml")

There are two main reasons for this. First, the hash-style syntax is very Ruby-specific. There are now Haml implementations in many languages, each of which has its own syntax for hashes (or dicts or associative arrays or whatever they're called). The HTML syntax will be adopted by all of them, so you can feel comfortable using Haml in whichever language you need.

Second, the hash-style syntax is quite verbose. %img{:src => "/images/haml.png", :alt => "Haml"} is eight characters longer than %img(src="/images/haml.png" alt="Haml"). Haml's supposed to be about writing templates quickly and easily; HTML-style attributes should help out a lot with that.

Ruby variables can be used as attribute values by omitting quotes. Local variables or instance variables can be used. For example:

%a(title=@title href=href) Stuff

This is the same as:

%a{:title => @title, :href => href} Stuff

Because there are no commas separating attributes, more complicated expressions aren't allowed. You can use #{} interpolation to insert complicated expressions in a HTML-style attribute, though:


Multiline Attributes

In general, Haml tries to keep individual elements on a single line. There is a multiline syntax for overflowing onto further lines, but it's intentionally awkward to use to encourage shorter lines.

However, there is one case where overflow is reasonable: attributes. Often a tag will simply have a lot of attributes, and in this case it makes sense to allow overflow. You can now stretch an attribute hash across multiple lines:

%script{:type => "text/javascript",
        :src  => "javascripts/script_#{2 + 7}"}

This also works for HTML-style attributes:

        src="javascripts/script_#{2 + 7}")

Note that for hash-style attributes, the newlines must come after commas.

Universal interpolation

In Haml 2.0, you could use == to interpolate Ruby code within a line of text using #{}. In Haml 2.2, the == is unnecessary; #{} can be used in any text. For example:

%p This is a really cool #{h what_is_this}!
But is it a #{h what_isnt_this}?

In addition, to { escape} or { unescape} the interpolated code, you can just add & or !, respectively, to the beginning of the line:

%p& This is a really cool #{what_is_this}!
& But is it a #{what_isnt_this}?

Flexible indentation

Haml has traditionally required its users to use two spaces of indentation. This is the universal Ruby style, and still highly recommended. However, Haml now allows any number of spaces or even tabs for indentation, provided:

  • Tabs and spaces are not mixed
  • The indentation is consistent within a given document

New Options


The :ugly option is not technically new; it was introduced in Haml 2.0 to make rendering deeply nested templates less painful. However, it's been greatly empowered in Haml 2.2. It now does all sorts of performance optimizations that couldn't be done before, and its use increases Haml's performance dramatically. It's enabled by default in production in Rails, and it's highly recommended for production environments in other frameworks.

:encoding {#encoding-option}

This option specifies the encoding of the Haml template when running under Ruby 1.9. It defaults to Encoding.default_internal or "utf-8". This is useful for making sure that you don't get weird encoding errors when dealing with non-ASCII input data.



This helper is being deprecated for the obvious reason that it conflicts with the Kernel#puts method. I'm ashamed I ever chose this name. Use haml_tag instead and spare me the embarrassment.

= haml_tag

A lot of people accidentally use "= haml_tag". This has always been wrong; haml_tag outputs directly to the template, and so should be used as "- haml_tag". Now it raises an error when you use =.



Haml 2.2 is fully compatible with Rails, from 2.0.6 to the latest revision of edge, 783db25.

Ruby 1.9

Haml 2.2 is also fully compatible with Ruby 1.9. It supports Ruby 1.9-style attribute hashes, and handles encoding-related issues (see the :encoding option).



There are numerous improvements to the Markdown filter. No longer will Haml attempt to use RedCloth's inferior Markdown implementation. Instead, it will look for all major Markdown implementations: RDiscount, RPeg-Markdown, Maruku, and BlueCloth.


There is now a :cdata filter for wrapping text in CDATA tags.


The :sass filter now uses options set in {Sass::Plugin}, if they're available.



The haml executable now takes -r and -I flags that act just like the same flags for the ruby executable. This allows users to load helper files when using Haml from the command line.

It also takes a --debug flag that causes it to spit out the Ruby code that Haml generates from the template. This is more for my benefit than anything, but you may find it interesting.


The html2haml executable has undergone significant improvements. Many of these are bugfixes, but there are also a few features. For one, it now understands CDATA tags and autodetects ERB files. In addition, a line containing just "- end" is now a Haml error; since it's not possible for html2haml to properly parse all Ruby blocks, this acts as a signal for the author that there are blocks to be dealt with.



Haml 2.2 supports a DTD for XHTML Mobile: !!! Mobile.


All the documentation for Haml 2.2, including this changelog, has been moved to YARD. YARD is an excellent documentation system, and allows us to write our documentation in Maruku, which is also excellent.

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