April 2012
Intermediate to advanced
294 pages
6h 27m
English
Content preview from Developing Web Applications with Haskell and YesodBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 4. Shakespearean Templates
Yesod uses the Shakespearean family of template languages as its standard approach to HTML, CSS, and JavaScript creation. This language family shares some common syntax, as well as overarching principles:
As little interference to the underlying language as possible, while providing conveniences where unobtrusive
Compile-time guarantees on well-formed content
Static type safety, greatly helping the prevention of XSS (cross-site scripting) attacks
Automated checking of valid URLs, whenever possible, through type-safe URLs
There is nothing inherently tying Yesod to these languages, or the other way around: each can be used independently of the other. This chapter will address these template languages on their own, while the remainder of the book will use them to enhance Yesod application development.
Synopsis
There are four main languages at play: Hamlet is an HTML templating language, Julius is for JavaScript, and Cassius and Lucius are both for CSS. Hamlet and Cassius are both whitespace-sensitive formats, using indentation to denote nesting. By contrast, Lucius is a superset of CSS, keeping CSS’s braces for denoting nesting. Julius is a simple passthrough language for producing JavaScript; the only added feature is variable interpolation.
Hamlet (HTML)
$doctype 5 <html> <head> <title>#{pageTitle} - My Site <link rel=stylesheet href=@{Stylesheet}> <body> <h1 .page-title>#{pageTitle} <p>Here is a list of your friends: $if null friends <p>Sorry, I lied, you ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.