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Slim is a template language whose goal is reduce the syntax to the essential parts without becoming cryptic.
Tag: v0.5.0

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


Slim is a Rails 3, Ruby 1.9.2 templating option. I do not intend on making a Rails 2.x compatible version. I don't think it would be difficult, so if you want it, I will happily accept contributions with tests.


Simply put, I wanted to see if I could pull of a template language that required minimum use of special characters and at least matched Erb's speed. Yes, Slim is speedy.


Include Slim in your Gemfile:

gem 'slim'

In config/application.rb, add the following line near the top:

require 'slim/rails'

That's it!

The syntax

I actually like the indentation and tag closing nature of Haml. I don't like the overall result of the markup though, it's a little cryptic. I'm sure, with practice, people read it like the Matrix, but it's never suited me. So why not try to improve it for me? There may be one or two other people with the same thoughts.

So here's what I came up with:

! doctype html
    title Slim Examples
    meta name="keywords" content="template language"
    h1 Markup examples
    div id="content" class="example1"
      p Nest by indentation

    = yield

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

    div id="footer"
      | Copyright © 2010 Andrew Stone

    = render partial: 'tracking_code' 

      | $(content).do_something();

How do I?

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 (followed by a space) 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

Set an attribute's value with a method?

  # Just use standard Ruby interpolation.

      - for user in users do 
        tr id="user_#{}"

Treat multiple lines of code as text that should bypass parsing.

  # Use a backtick 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...

Things to know:

  • Standard Ruby syntax after '-' and '='
    • end is not required
  • 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 ('|') a backtick ('`').
  • Indentation matters, but it's not as strict as Haml.
    • If you want to indent 2 spaces, then 5. It's your choice. To nest markup you only need to indent by one space, the rest is gravy.

Line indicators:

Please note that all line indicators must be followed by a space

  • |
    • The pipe tells Slim to just copy the line. It essentially escapes any processing.
  • `
    • Same as the pipe ('|').
  • -
    • 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).
  • !
    • This is a directive. Most common example: ! doctype html renders <!doctype html>

Please add feature requests and bugs to the Github issue tracker.

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