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Haml Changelog

  • Table of contents {:toc}

2.4.0 (Unreleased)

haml_tag and haml_concat Improvements

haml_tag with CSS Selectors

The {Haml::Helpers#haml_tag haml_tag} helper can now take a string using the same class/id shorthand as in standard Haml code. Manually-specified class and id attributes are merged, again as in standard Haml code. For example:

haml_tag('#foo') #=> <div id='foo' />
haml_tag('.bar) #=> <div class='bar' />
haml_tag('') #=> <span class='bar' id='foo' />
haml_tag('', :class => 'abc') #=> <span class='abc bar' id='foo' />
haml_tag('', :id => 'abc') #=> <span class='bar' id='abc_foo' />

Cheers, S. Burkhard.

haml_tag with Multiple Lines of Content

The {Haml::Helpers#haml_tag haml_tag} helper also does a better job of formatting tags with multiple lines of content. If a tag has multiple levels of content, that content is indented beneath the tag. For example:

haml_tag(:p, "foo\nbar") #=>
  # <p>
  #   foo
  #   bar
  # </p>

haml_tag with Multiple Lines of Content

Similarly, the {Haml::Helpers#haml_concat haml_concat} helper will properly indent multiple lines of content. For example:

haml_tag(:p) {haml_concat "foo\nbar"} #=>
  # <p>
  #   foo
  #   bar
  # </p>

haml_tag and haml_concat with :ugly

When the { :ugly option} is enabled, {Haml::Helpers#haml_tag haml_tag} and {Haml::Helpers#haml_concat haml_concat} won't do any indentation of their arguments.

Basic Tag Improvements

  • It's now possible to customize the name used for { object reference} for a given object by implementing the haml_object_ref method on that object. This method should return a string that will be used in place of the class name of the object in the generated class and id.

  • All attribute values may be non-String types. Their #to_s method will be called to convert them to strings. Previously, this only worked for attributes other than class.

More Powerful :autoclose Option

The { :attributes} option can now take regular expressions that specify which tags to make self-closing.

--double-quote-attributes Option

The Haml executable now has a --double-quote-attributes option (short form: -q) that causes attributes to use a double-quote mark rather than single-quote.

haml-spec Integration

We've added the cross-implementation tests from the haml-spec project to the standard Haml test suite, to be sure we remain compatible with the base functionality of the many and varied Haml implementations.

Ruby 1.9 Support

  • Haml and html2haml now produce more descriptive errors when given a template with invalid byte sequences for that template's encoding, including the line number and the offending character.

  • Haml and html2haml now accept Unicode documents with a byte-order-mark.

:css Filter

Haml now supports a { :css filter} that surrounds the filtered text with <style> and CDATA tags.

html2haml Improvements

  • Ruby blocks within ERB are now supported. The Haml code is properly indented and the ends are removed. This includes methods with blocks and all language constructs such as if, begin, and case. For example:

    <% content_for :footer do %>
      <p>Hi there!</p>
    <% end %>

    is now transformed into:

    - content_for :footer do
      %p Hi there!

    Thanks to Jack Chen and Dr. Nic Williams for inspiring this and creating the first draft of the code.

  • Inline HTML text nodes are now transformed into inline Haml text. For example, <p>foo</p> now becomes %p foo, whereas before it became:


    The same is true for inline comments, and inline ERB when running in ERB mode: <p><%= foo %></p> will now become %p= foo.

  • ERB included within text is now transformed into Ruby interpolation. For example:

      Foo <%= bar %> baz!
      Flip <%= bang %>.

    is now transformed into:

      Foo #{bar} baz!
      Flip #{bang}.
  • <script> tags are now transformed into :javascript filters, and <style> tags into :css filters. and indentation is preserved. For example:

    <script type="text/javascript">
      function foo() {
        return 12;

    is now transformed into:

      function foo() {
        return 12;
  • <pre> and <textarea> tags are now transformed into the :preserve filter. For example:


    is now transformed into:

  • Self-closing tags (such as <br />) are now transformed into self-closing Haml tags (like %br/).

  • IE conditional comments are now properly parsed.

  • Attributes are now output in a more-standard format, without spaces within the curly braces (e.g. %p{:foo => "bar"} as opposed to %p{ :foo => "bar" }).

  • IDs and classes containing # and . are now output as string attributes (e.g. %p{:class => ""}).

  • Attributes are now sorted, to maintain a deterministic order.

  • Multi-line ERB statements are now properly indented, and those without any content are removed.

Backwards Incompatibilities: Must Read!

  • The puts helper has been removed. Use {Haml::Helpers#haml_concat} instead.


Tagged on GitHub.

  • The form_tag Rails helper is now properly marked as HTML-safe when using Rails' XSS protection with Rails 2.3.5.

  • Calls to defined? shouldn't interfere with Rails' autoloading in very old versions (1.2.x).

  • Fix a bug where calls to ActionView's render method with blocks and layouts wouldn't work under the Rails 3.0 beta.

  • Fix a bug where the closing tags of nested calls to {Haml::Helpers#haml_concat} were improperly escaped under the Rails 3.0 beta.


Tagged on GitHub.

  • Fix a bug with the integration with Rails' XSS support. In particular, correctly override safe_concat.


Tagged on GitHub.

  • Support the new XSS-protection API used in Rails 3.

  • Use Rails.env rather than RAILS_ENV when running under Rails 3.0. Thanks to Duncan Grazier.

  • Add a --unix-newlines flag to all executables for outputting Unix-style newlines on Windows.

  • Fix a couple bugs with the :erb filter: make sure error reporting uses the correct line numbers, and allow multi-line expressions.

  • Fix a parsing bug for HTML-style attributes including #.


Tagged on GitHub.

  • Fix compilation of HTML5 doctypes when using html2haml.

  • nil values for Sass options are now ignored, rather than raising errors.


Tagged on GitHub.

  • Abstract out references to ActionView::TemplateError, ActionView::TemplateHandler, etc. These have all been renamed to ActionView::Template::* in Rails 3.0.


Tagged on GitHub.

  • Allow if statements with no content followed by else clauses. For example:

    • if foo
    • else bar


Tagged on GitHub.

  • Don't print warnings when escaping attributes containing non-ASCII characters in Ruby 1.9.

  • Don't crash when parsing an XHTML Strict doctype in html2haml.

  • Support the HTML5 doctype in an XHTML document by using !!! 5 as the doctype declaration.


Tagged on GitHub.

  • Allow users to specify { :encoding => "ascii-8bit"} even for templates that include non-ASCII byte sequences. This makes Haml templates not crash when given non-ASCII input that's marked as having an ASCII encoding.

  • Fixed an incompatibility with Hpricot 0.8.2, which is used for html2haml.


Tagged on GitHub.

There were no changes made to Haml between versions 2.2.11 and 2.2.12.


Tagged on GitHub.

  • Fixed a bug with XSS protection where HTML escaping would raise an error if passed a non-string value. Note that this doesn't affect any HTML escaping when XSS protection is disabled.

  • Fixed a bug in outer-whitespace nuking where whitespace-only Ruby strings blocked whitespace nuking beyond them.

  • Use ensure to protect the resetting of the Haml output buffer against exceptions that are raised within the compiled Haml code.

  • Fix an error line-numbering bug that appeared if an error was thrown within loud script (=). This is not the best solution, as it disables a few optimizations, but it shouldn't have too much effect and the optimizations will hopefully be re-enabled in version 2.4.

  • Don't crash if the plugin skeleton is installed and rake gems:install is run.

  • Don't use RAILS_ROOT directly. This no longer exists in Rails 3.0. Instead abstract this out as Haml::Util.rails_root. This changes makes Haml fully compatible with edge Rails as of this writing.


Tagged on GitHub.

  • Fixed a bug where elements with dynamic attributes and no content would have too much whitespace between the opening and closing tag.

  • Changed rails/init.rb away from loading init.rb and instead have it basically copy the content. This allows us to transfer the proper binding to Haml.init_rails.

  • Make sure Haml only tries to enable XSS protection integration once all other plugins are loaded. This allows it to work properly when Haml is a gem and the rails_xss plugin is being used.

  • Mark the return value of Haml templates as HTML safe. This makes Haml partials work with Rails' XSS protection.


Tagged on GitHub.

  • 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.


Tagged on GitHub.

  • 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.


Tagged on GitHub.

  • 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.


Tagged on GitHub.

  • 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"}).


Tagged on GitHub.

  • 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.


Tagged on GitHub.

  • 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.


Tagged on GitHub.

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


Tagged on GitHub.

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.


Tagged on GitHub.

Haml 2.2.1 is a minor bug-fix release.


Tagged on GitHub.

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_concat 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.