¶ Haml (Ruby)
¶ Web Technologies
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INTRODUCTION ARTICLE
The world of web development has always been a conversation between humans and machines—people trying to express ideas clearly and efficiently, and computers doing their best to interpret those ideas without misunderstanding. Somewhere in that long conversation, developers began looking for ways to write markup that felt less like wrestling with angle brackets and more like shaping ideas into form. That instinct, the desire to make code feel graceful and expressive, is what gave rise to tools like Haml.
Haml isn’t just another templating language. It’s a quiet rebellion against the clutter that can creep into HTML when projects grow large or when developers are moving quickly. It encourages elegance, readability, and a kind of compositional calm that makes working with markup feel almost meditative. At its core, Haml is born from the Ruby community’s long-standing love for expressive code—code that reads like a conversation rather than a command. If Ruby is a language that treats programming as a craft, then Haml is its way of sculpting views with minimal fuss and maximum clarity.
This course, stretching across a hundred articles, is designed to gently immerse you into that world. It isn’t only about Haml—not in the isolated, technical sense. It’s about everything that surrounds it: the philosophy that led to its creation, the way it fits into the larger web ecosystem, and how it interacts with other technologies that shape the experience of building modern websites. By the time you finish the last article, Haml won’t feel like a quirky alternative syntax. It will feel like a natural way to think about markup—a mindset as much as a language.
Working with Haml changes how people write code. Some first encounter it while diving into Ruby on Rails applications and wonder why their templates look so clean compared to the tangled mixture of tags and indentation they might be used to. Others find it after long stretches of wrestling with HTML and realize that there’s a way to express the same structure with far fewer distractions. It’s almost surprising how much visual noise disappears when you shift from HTML’s many closing tags to Haml’s indentation-based structure. Everything becomes quieter. The page breathes.
This course is built around that feeling—the sense that markup should feel pleasant to write. Over the coming articles, the goal is not only to teach syntax but to sharpen your intuition about how markup interacts with layout, logic, stylesheets, and the broader environment of a web application. Every technology has a story, and Haml’s story is tied to a desire to make coding feel humane. If you’ve ever felt weighed down by templates cluttered with repetitive tags or struggled to keep track of deeply nested HTML, Haml will feel like a long-awaited breath of fresh air.
And while Haml is firmly rooted in the Ruby ecosystem, its usefulness extends far beyond the language itself. Understanding it teaches you something important about the web: that the way we write markup affects more than the browser’s ability to render a page. It affects our ability to think clearly about structure, hierarchy, and design. Clean markup leads to clean thought. Clean thought leads to better applications.
As you progress through the course, you’ll see how Haml interacts with the larger universe of web technologies—CSS preprocessors like Sass, component-based rendering patterns, server-side frameworks, front-end scripts, and even design systems that emphasize semantics and accessibility. You’ll also explore the practical side: how to convert existing HTML into Haml, how to integrate it into a Rails project, how to manage partials, helpers, and layouts, and how to keep your views maintainable as your application evolves.
But before diving into any technical detail, it helps to start with a sense of the landscape. The modern web is a fascinating blend of longstanding traditions and constantly evolving ideas. HTML remains one of the oldest pillars of the internet, yet we continually find new ways to work with it more effectively. This push toward better expression—toward code that feels natural to write and understand—is a recurring theme throughout web development history. Whether it was early templating engines, the emergence of JSX, or the widespread adoption of server-side rendering frameworks, developers have always searched for syntax that lets them think clearly and build quickly.
Haml fits squarely into that tradition. It is shaped by a philosophy that values clarity and concision. Instead of forcing developers to write verbose constructs, it lets them express the structure of a page through indentation and minimal punctuation. The result is a kind of visual poetry—markup that conveys hierarchy through space rather than symbols. Once your eyes adjust to that rhythm, going back to traditional HTML can feel surprisingly cumbersome.
One of the quiet joys of writing in Haml is the way it encourages you to think about the essentials. Without closing tags to juggle or repetitive structures to worry about, your focus shifts to the meaning of the markup rather than its mechanics. You begin to consider which elements truly matter, which classes are necessary, and how your layout fits together. This mindset often leads to cleaner, more semantic HTML outputs—something that benefits users, designers, and fellow developers alike.
And Haml doesn’t exist in isolation. It plays beautifully with Ruby’s sense of expressiveness. Ruby code embedded in Haml feels smooth and intentional, a natural continuation of the language’s emphasis on elegance. As you learn more about using Ruby inside your templates—whether through helpers, logic, or cleanly separated partials—you’ll begin to appreciate how Haml helps maintain a clear separation between structure and behavior. Your templates become more readable, your logic becomes cleaner, and your codebase becomes easier to maintain.
Throughout this course, you’ll find yourself encountering not only Haml, but the broader disciplines it touches—accessibility, semantic markup, responsive design, and the growing world of component-driven interfaces. Learning Haml gives you an opportunity to revisit these essential concepts from a fresh perspective. Everything feels slightly more approachable when the syntax is gentle and the structure is clear.
You’ll also explore how Haml fits into collaborative environments. When multiple developers are working on the same project, a consistent, concise templating language can reduce friction and misunderstandings. Haml’s simplicity makes it easier to onboard new team members. Its readability allows designers and developers to communicate more effectively. And because the syntax discourages unnecessary clutter, large codebases stay cleaner over time.
One of the interesting things you’ll discover is how Haml affects your sense of flow while coding. There’s something intangible about the shift from typing long, repetitive markup to working with a syntax that responds to indentation. Your hands move differently. Your mental load changes. Code feels more like shaping a structure and less like assembling a puzzle of brackets and slashes. This may sound subtle, but the long-term impact can be significant, especially when building complex views or revisiting templates months later.
As the course unfolds, you’ll also encounter the evolution of Haml itself. Over the years, it has adapted to new versions of Ruby, new conventions in the Rails ecosystem, and new expectations for templating languages. You’ll learn about its features, its quirks, and the small details that distinguish polished templates from those that simply “work.” You’ll see how Haml handles attributes, filters, whitespace, and inline Ruby, as well as how it integrates with layouts, partial rendering, and content-for blocks.
Of course, not everything in Haml is perfect or universally adored—no technology ever is. Part of becoming proficient involves understanding its trade-offs. Some developers prefer the explicitness of HTML. Others enjoy markup that mirrors traditional document structures more closely. Exploring these perspectives will help you become not just a Haml user, but a thoughtful web developer capable of choosing the right tool for each situation.
By the later parts of this course, you’ll be comfortable enough with Haml that your attention can shift toward larger themes: how to architect view layers that scale; how to apply design patterns to markup; how to keep templates lean even as your application grows in complexity; how to integrate Haml with component libraries; and how to maintain a consistent design language across large codebases. These lessons carry beyond Haml—they are skills you can take into any environment, any framework, any team.
Eventually, you’ll also explore the relationship between Haml and performance. While templating languages rarely dominate performance discussions, understanding how rendering works, how caching can be applied, and how to reduce template overhead gives you a deeper appreciation for the invisible machinery behind every request. As your understanding grows, so does your ability to build applications that feel fast, responsive, and reliable.
The final stretch of the course will introduce you to the future-facing aspects of view development: hybrid rendering techniques, integration with JavaScript frameworks, and the subtle line between server-side and client-side concerns. Even though Haml is a server-side templating language, the modern web constantly blurs boundaries. Learning to maneuver smoothly between Ruby-rendered views and dynamic front-end interactions is a valuable skill—and Haml, with its clarity and concision, helps keep that complexity manageable.
But before all of that comes the most important part: enjoying the process of learning. Web development can sometimes feel overwhelming—dozens of technologies, endless updates, shifting best practices. This course is designed to make the journey feel grounded, approachable, and even pleasurable. Each article builds gently on the last. The path is gradual, steady, and thoughtful. You’ll learn at a pace that keeps curiosity alive without letting confusion take hold.
If you’ve ever wished for a way to write markup that feels light instead of heavy, expressive instead of mechanical, Haml will feel like home. If you’ve ever wished for a clearer understanding of the web’s underlying patterns, this course will guide you forward. And if you’ve ever wondered how professionals build applications that are elegant, maintainable, and scalable, you will find many of the answers woven into these articles.
By the time you reach the end of all one hundred, something subtle but important will have changed. Markup will no longer feel like a separate universe from logic or design. The web will no longer seem like a maze of disconnected technologies. You’ll see the patterns that tie everything together—patterns that transcend languages, frameworks, and fads.
And somewhere along that journey, Haml will stop being just a syntax and become a way of thinking: clear, expressive, uncluttered.
Welcome to the beginning. The web is full of possibilities, and Haml offers a beautiful entry point into its deeper layers. The path ahead is long, but rich, and you’re now taking the first steps into a way of building that values clarity, craft, and calm.
Let’s begin.
¶ Haml (Ruby)
¶ Part 1: Introduction to Haml
1. What is Haml? An Introduction to HTML Abstraction Markup Language
2. Why Use Haml for Web Development?
3. Setting Up Your Ruby Environment for Haml
4. Installing and Configuring Haml
5. Understanding the Basic Syntax of Haml
6. The Advantages of Haml over HTML
7. Creating Your First Haml File
8. Converting HTML to Haml
9. Basic Haml Elements: Tags and Nesting
10. Running Haml from the Command Line
¶ Part 2: Core Haml Syntax
11. Understanding the Indentation Rules in Haml
12. Using Whitespace and Newlines in Haml
13. Haml Syntax for Elements and Attributes
14. Creating and Nesting HTML Tags in Haml
15. Commenting in Haml
16. Using Plain Ruby Code in Haml
17. Working with Class and ID Attributes in Haml
18. Understanding the % Symbol in Haml
19. Creating Self-Closing Tags in Haml
20. Writing Simple Forms with Haml
¶ Part 3: Advanced Haml Syntax
21. Understanding Ruby Code in Haml and Logic Blocks
22. Embedding Ruby Variables in Haml
23. Working with Conditionals in Haml
24. Using Loops in Haml for Dynamic Content
25. Rendering Partial Views with Haml
26. Refining Layouts with Haml
27. Handling Escaped and Unescaped Content
28. Using Ruby Functions and Helpers in Haml
29. Building Custom Haml Helpers for Reusable Code
30. Exploring Dynamic Tag Generation in Haml
¶ Part 4: Haml in Ruby on Rails
31. Integrating Haml with Ruby on Rails
32. Setting Up Rails to Use Haml
33. Converting an HTML-based Rails App to Haml
34. Working with Rails View Helpers in Haml
35. Using Haml for Rails Forms
36. Rendering Forms with Multiple Fields in Haml
37. Using Haml for Layouts and Templates in Rails
38. Partial Views and Shared Components in Rails with Haml
39. Working with Rails' Asset Pipeline in Haml
40. Debugging Haml Errors in Rails Applications
¶ Part 5: Styling and UI with Haml
41. Embedding CSS in Haml for Styling
42. Using External CSS with Haml
43. Creating Inline Styles in Haml
44. Integrating Haml with CSS Frameworks (Bootstrap, Foundation)
45. Creating Custom CSS Classes with Haml
46. Building a Responsive Layout with Haml
47. Leveraging Haml to Generate Semantic HTML
48. Working with Images and Backgrounds in Haml
49. Adding Fonts and Icons to Haml Views
50. Integrating JavaScript Libraries and Frameworks with Haml
¶ Part 6: Using Advanced Features
51. Advanced Ruby Code in Haml Views
52. Creating Complex Nested Elements in Haml
53. Managing Multiple Layouts in Haml
54. Using Haml with AJAX for Dynamic Updates
55. Optimizing Haml Templates for Performance
56. Working with JavaScript Assets in Haml
57. Haml for SEO-Friendly Markup
58. Implementing User Authentication Views in Haml
59. Advanced Conditional Logic in Haml Templates
60. Dynamic Data Rendering with Haml and Ruby on Rails
¶ Part 7: Working with Forms in Haml
61. Understanding Haml Form Helpers in Rails
62. Creating Simple Forms in Haml
63. Building Multi-Field Forms with Haml
64. Adding File Uploads to Haml Forms
65. Using Form Validation in Haml
66. Working with Checkboxes, Radio Buttons, and Select Boxes in Haml
67. Styling Form Elements with CSS in Haml
68. Building Complex Nested Forms in Haml
69. Using Haml to Handle Form Submission Feedback
70. Customizing Rails Form Helpers in Haml
¶ Part 8: Debugging and Optimization
71. Common Haml Syntax Errors and How to Fix Them
72. Debugging Ruby Code Embedded in Haml
73. Improving Haml Template Performance
74. Understanding the Performance Overhead of Haml
75. Reducing Redundant Code in Haml Templates
76. Caching Views in Rails with Haml Templates
77. Using Haml to Minimize HTML Output
78. Profiling Haml Rendering Speed
79. Best Practices for Writing Efficient Haml Code
80. Optimizing Haml Code for Large Applications
¶ Part 9: Testing Haml Templates
81. Setting Up Unit Tests for Haml Templates
82. Testing Haml Views in Rails
83. Mocking Data in Haml for Testing
84. Automating Browser Tests with Haml and Capybara
85. Writing Assertions for Haml Views
86. Handling Edge Cases in Haml Tests
87. Unit Testing Haml Forms in Rails
88. Using RSpec for Haml View Testing
89. Testing Layouts and Partials in Haml
90. End-to-End Testing with Haml Templates
¶ Part 10: Advanced Topics in Haml
91. Integrating Haml with External APIs for Dynamic Content
92. Creating Reusable Components in Haml
93. Building Complex Nested Structures in Haml
94. Advanced Ruby on Rails and Haml Integration
95. Building Multi-Language Sites with Haml
96. Using Haml with Webpack and JavaScript Assets
97. Creating Highly Customizable Templates with Haml
98. Version Control for Haml Templates in Large Projects
99. Building Progressive Web Apps (PWA) with Haml
100. Maintaining and Upgrading Haml Templates in Production