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Slim is a template language whose goal is to reduce the view syntax to the essential parts without becoming cryptic.


Slim is a fast, lightweight templating engine with support for Rails 3. It has been tested on Ruby 1.9.2 and Ruby/REE 1.8.7.

Slim's core syntax is guided by one thought: "What's the minimum required to make this work".

As more people have contributed to Slim, there have been optional syntax additions influenced from their use of Haml and Jade. The Slim team is open to these optional additions because we know beauty is in the eye of the beholder.

Slim uses Temple for parsing/compilation and is also integrated into Tilt, so it can be used together with Sinatra or plain Rack.


Within the Rails community, Erb and Haml are without doubt the two most popular templating engines. However, Erb's syntax is cumbersome and Haml's syntax can be quite cryptic to the uninitiated.

Slim was born to bring a minimalist syntax approach with speed. If people chose not to use Slim, it would not be because of speed.

Yes, Slim is speedy! Benchmarks are provided at the end of this README file. Don't trust the numbers? That's as it should be. Therefore we provide a benchmark rake task so you could test it yourself (rake bench).


Install Slim as a gem:

gem install slim

Include Slim in your Gemfile:

gem 'slim'

That's it! Now, just use the .slim extension and you're good to go.

If you want to use the Slim template directly, you can use the Tilt interface:['template.slim'].render(scope), optional_option_hash).render(scope) { source }.render(scope)

Syntax Highlighters

Syntax highlight support for Emacs is included in the extra folder. There are also Vim and Textmate plugins.

Template Converters

For Haml, there is a Haml2Slim converter. Please check out the issue tracker to see the status of the varies converters.

The syntax

As a Rails developer, you might already be very familiar with Haml's syntax and you think it is fantastic - until you entered the magic kingdom of node.js and got introduced to Jade.

Slim's syntax has been influenced by both Haml and Jade.

Here's a quick example to demonstrate what a Slim template looks like:

doctype html
    title Slim Examples
    meta name="keywords" content="template language"

    h1 Markup examples
      p Nest by indentation

    = yield

    - unless items.empty?
        - for item in items do
            td =
            td = item.price
    - else
      p No items found

      | Copyright © 2010 Andrew Stone

    = render 'tracking_code'

      | $(content).do_something();

Language features

Line indicators


The pipe tells Slim to just copy the line. It essentially escapes any processing.


The single quote tells Slim to copy the line (similar to |), but makes sure that a single trailing space is appended.


The dash denotes control code (similar to Haml). Examples of control code are loops and conditionals.


The equal sign tells Slim it's a Ruby call that produces output to add to the buffer (similar to Erb and Haml).


Same as the single equal sign (=), except that it adds a trailing whitespace.


Same as the single equal sign (=), but does not go through the escape_html method.


Same as the double equal sign (==), except that it adds a trailing whitespace.


Use the forward slash for ruby code comments - anything after it won't get displayed in the final render.


Use the forward slash immediately followed by an exclamation mark for html comments (<!-- -->).

Things to know

Standard Ruby syntax after - and =

end is forbidden behind -. Blocks are defined only by indentation.

Can put content on same line or nest it.

If you nest content (e.g. put it on the next line), start the line with a pipe (|) or a single quote (').

Indentation matters, but it's not as strict as Haml.

If you want to first indent 2 spaces, then 5 spaces, it's your choice. To nest markup you only need to indent by one space, the rest is gravy.

If your ruby code needs to use multiple lines, append a \ at the end of the lines, for example:

= javascript_include_tag \
   "jquery", \

Wrap attributes with delimiters

If a delimiter makes the syntax more readable for you, you can use the characters {...}, (...), [...] to wrap the attributes.

  h1(id="logo") = page_logo
  h2[id="tagline" class="small tagline"] = page_tagline

If you wrap the attributes, you can spread them across multiple lines:

h2[ id="tagline"
    class="small tagline"] = page_tagline

Add content to a tag

Either start on the same line as the tag

  h1 id="headline" Welcome to my site.

Or nest it. Note: Must use a pipe or a backtick to escape processing

  h1 id="headline"
    | Welcome to my site.

Add content to a tag with code

Can make the call on the same line

  h1 id="headline" = page_headline

Or nest it.

  h1 id="headline"
    = page_headline

Shortcut form for id and class attributes

Similarly to Haml, you can specify the id and class attributes in the following shortcut form Note: the shortcut form does not evaluate ruby code

    = page_headline
    = page_tagline
    = show_content

this is the same as

  h1 id="headline"
    = page_headline
  h2 id="tagline" class="small tagline"
    = page_tagline
  div class="content"
    = show_content

Inline tags

Sometimes you may want to be a little more compact and inline the tags.

  li.first: a href="/a" A link
  li: a href="/b" B link

For readability, don't forget you can wrap the attributes.

  li.first: a[href="/a"] A link
  li: a[href="/b"] B link

Set an attribute's value with a method

  • Alternative 1: Use parentheses (), {}, []. The code in the parentheses will be evaluated.
  • Alternative 2: If the code doesn't contain any spaces you can omit the parentheses.
  • Alternative 3: Use standard ruby interpolation #{}

Attributes will always be html escaped.

    - for user in users do
      td id="user_#{}" class=user.role
        a href=user_action(user, :edit) Edit #{}
        a href={path_to_user user} =

Evaluate ruby code in text

Use standard Ruby interpolation. The text will be html escaped by default.

  h1 Welcome #{} to the show.
  | Unescaped #{{content}} is also possible.

To escape the interpolation (i.e. render as is)

  h1 Welcome \#{} to the show.

Skip the html escaping

Use a double equal sign

  h1 id="headline"
    == page_headline

Alternatively, if you prefer to use single equal sign, you may do so by setting the disable_escape option to true.

Slim::Engine.default_options[:disable_escape] = true

Treat multiple lines of code as text that should bypass parsing

Use a pipe (|) or single quote (') to start the escape. Each following line that is indented greater than the backtick is copied over.

      This is a test of the text block.

The parsed result of the above:

<body><p>This is a test of the text block.</p></body>

The left margin is set at the indent of the backtick + one space. Any additional spaces will be copied over.

    |  This line is on the left margin.
        This line will have one space in front of it.
          This line will have two spaces in front of it.
            And so on...

Add comments

Use / for ruby code comments and /! for html comments

    / This line won't get displayed.
      Neither does this line.
    /! This will get displayed as html comments.

The parsed result of the above:

<body><p><!--This will get displayed as html comments.--></p></body>


The benchmarks are only to demonstrate that Slim's speed should not be a determining factor in your template choice. Even if we don't agree, we'd prefer you to use any other reason for choosing another template language.

# Linux + Ruby 1.9.2, 1000 iterations

                      user     system      total        real
(1) erb           0.680000   0.000000   0.680000 (  0.810375)
(1) erubis        0.510000   0.000000   0.510000 (  0.547548)
(1) fast erubis   0.530000   0.000000   0.530000 (  0.583134)
(1) slim          4.330000   0.020000   4.350000 (  4.495633)
(1) haml          4.680000   0.020000   4.700000 (  4.747019)
(1) haml ugly     4.530000   0.020000   4.550000 (  4.592425)

(2) erb           0.240000   0.000000   0.240000 (  0.235896)
(2) erubis        0.180000   0.000000   0.180000 (  0.185349)
(2) fast erubis   0.150000   0.000000   0.150000 (  0.154970)
(2) slim          0.050000   0.000000   0.050000 (  0.046685)
(2) haml          0.490000   0.000000   0.490000 (  0.497864)
(2) haml ugly     0.420000   0.000000   0.420000 (  0.428596)

(3) erb           0.030000   0.000000   0.030000 (  0.033979)
(3) erubis        0.030000   0.000000   0.030000 (  0.030705)
(3) fast erubis   0.040000   0.000000   0.040000 (  0.035229)
(3) slim          0.040000   0.000000   0.040000 (  0.036249)
(3) haml          0.160000   0.000000   0.160000 (  0.165024)
(3) haml ugly     0.150000   0.000000   0.150000 (  0.146130)

(4) erb           0.060000   0.000000   0.060000 (  0.059847)
(4) erubis        0.040000   0.000000   0.040000 (  0.040770)
(4) slim          0.040000   0.000000   0.040000 (  0.047389)
(4) haml          0.190000   0.000000   0.190000 (  0.188837)
(4) haml ugly     0.170000   0.000000   0.170000 (  0.175378)

1. Uncached benchmark. Template is parsed every time.
   Activate this benchmark with slow=1.

2. Cached benchmark. Template is parsed before the benchmark.
   The ruby code generated by the template engine might be evaluated every time.
   This benchmark uses the standard API of the template engine.

3. Compiled benchmark. Template is parsed before the benchmark and
   generated ruby code is compiled into a method.
   This is the fastest evaluation strategy because it benchmarks
   pure execution speed of the generated ruby code.

4. Compiled Tilt benchmark. Template is compiled with Tilt, which gives a more
   accurate result of the performance in production mode in frameworks like
   Sinatra, Ramaze and Camping. (Rails still uses its own template


Slim provides an extensive test-suite based on minitest. You can run the tests with 'rake test' and the rails integration tests with 'rake test:rails'.

Travis-CI is used for continous integration testing:!/stonean/slim

Slim is working well on all major Ruby implementations:

  • Ruby 1.8.7
  • Ruby 1.9.2
  • Ruby 1.9.3
  • Ruby EE
  • JRuby
  • Rubinius 2.0


This project is released under the MIT license.



Slim related projects