Hamlit is another implementation of Haml. With some limitations by design for performance, Hamlit is 8.54x times faster than original haml gem in this benchmark, which is an HTML-escaped version of slim-template/slim's one for fairness.

Code Quality Rank: L4
Monthly Downloads: 753,830
Programming language: Ruby
License: MIT License
Latest version: v3.0.1

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Gem Version test

Hamlit is a high performance Haml implementation.


What is Hamlit?

Hamlit is another implementation of Haml. With some [limitations](REFERENCE.md#limitations) by design for performance, Hamlit is 1.94x times faster than original haml gem in [this benchmark](benchmark/slim/run-benchmarks.rb), which is an HTML-escaped version of slim-template/slim's one for fairness. (Result on Travis)

      hamlit v2.13.0:   247404.4 i/s
        erubi v1.9.0:   244356.4 i/s - 1.01x slower
         slim v4.1.0:   238254.3 i/s - 1.04x slower
         faml v0.8.1:   197293.2 i/s - 1.25x slower
         haml v5.2.0:   127834.4 i/s - 1.94x slower

Why is Hamlit faster?

Less string concatenation by design

As written in [limitations](REFERENCE.md#limitations), Hamlit drops some not-so-important features which require works on runtime. With the optimized language design, we can reduce the string concatenation to build attributes.

Static analyzer

Hamlit analyzes Ruby expressions with Ripper and render it on compilation if the expression is static. And Hamlit can also compile string literal with string interpolation to reduce string allocation and concatenation on runtime.

C extension to build attributes

While Hamlit has static analyzer and static attributes are rendered on compilation, dynamic attributes must be rendered on runtime. So Hamlit optimizes rendering on runtime with C extension.


Hamlit currently supports Ruby 2.1 and higher. See [REFERENCE.md](REFERENCE.md) for detail features of Hamlit.


Add this line to your application's Gemfile or just replace gem "haml" with gem "hamlit". It enables rendering by Hamlit for *.haml automatically.

gem 'hamlit'

If you want to use view generator, consider using hamlit-rails.


Replace gem "haml" with gem "hamlit" in Gemfile, and require "hamlit".

While Haml disables escape_html option by default, Hamlit enables it for security. If you want to disable it, please write:

set :haml, { escape_html: false }

Command line interface

You can see compiled code or rendering result with "hamlit" command.

$ gem install hamlit
$ hamlit --help
  hamlit compile HAML    # Show compile result
  hamlit help [COMMAND]  # Describe available commands or one specific command
  hamlit parse HAML      # Show parse result
  hamlit render HAML     # Render haml template
  hamlit temple HAML     # Show temple intermediate expression

$ cat in.haml
- user_id = 123
%a{ href: "/users/#{user_id}" }

# Show compiled code
$ hamlit compile in.haml
_buf = [];  user_id = 123;
; _buf << ("<a href='/users/".freeze); _buf << (::Hamlit::Utils.escape_html((user_id))); _buf << ("'></a>\n".freeze); _buf = _buf.join

# Render html
$ hamlit render in.haml
<a href='/users/123'></a>


Test latest version

# Gemfile
gem 'hamlit', github: 'k0kubun/hamlit', submodules: true


Contributions are welcomed. It'd be good to see Temple's EXPRESSIONS.md to learn Temple which is a template engine framework used in Hamlit.

$ git clone --recursive https://github.com/k0kubun/hamlit
$ cd hamlit
$ bundle install

# Run all tests
$ bundle exec rake test

# Run one test
$ bundle exec ruby -Ilib:test -rtest_helper test/hamlit/line_number_test.rb -l 12

# Show compiling/rendering result of some template
$ bundle exec exe/hamlit compile in.haml
$ bundle exec exe/hamlit render in.haml

# Use rails app to debug Hamlit
$ cd sample/rails
$ bundle install
$ bundle exec rails s

Reporting an issue

Please report an issue with following information:

  • Full error backtrace
  • Haml template
  • Ruby version
  • Hamlit version
  • Rails/Sinatra version

Coding styles

Please follow the existing coding styles and do not send patches including cosmetic changes.


Copyright (c) 2015 Takashi Kokubun

*Note that all licence references and agreements mentioned in the Hamlit README section above are relevant to that project's source code only.