11 HAML
| (require koyo/haml) | package: koyo-lib |
haml is a convenience macro for generating xexprs with less boilerplate. Its syntax is inspired by haml – whence its name – but if you’ve used Clojure’s hiccup or any similar templating language (like jade or pug), then haml will seem familiar to you.
11.1 Syntax
syntax
(haml element ...+)
element = (selector attributes element ...) | (selector element ...) | symbol | unless | when | splice | expr selector = :tag-name | .class-name | .class-name-1.class-name-2.class-name-n#id | :tag-name.class-name | :tag-name.class-name#id symbol = &name attributes = ((:attribute-name maybe-expr) ...) unless = (unless cond-expr e0 e ...) when = (when cond-expr e0 e ...) splice = ,@e
Literal numbers and strings are returned unmodified:
> (haml 1) 1
> (haml "hello") "hello"
Identifiers that start with an & symbol are returned with said symbol stripped off:
> (haml &mdash) 'mdash
Other identifiers are evaluated from the enclosing environment:
> (let ([a-symbol 'mdash]) (haml a-symbol)) 'mdash
Element tags start with a colon:
> (haml (:h1 "Hello World")) '(h1 () "Hello World")
Id and class attributes can be attached to a tag via a shorthand syntax:
> (haml (:h1.title#main-title "Hello World")) '(h1 ((id "main-title") (class "title")) "Hello World")
Tag names are optional if a class name is provided:
> (haml (.content (:h1.title "Hello World"))) '(div ((class "content")) (h1 ((class "title")) "Hello World"))
Lists of elements can be spliced in using the ,@e syntax:
> (haml (.content (:ul.items ,@(for/list ([it (list "a" "b" "c")]) (haml (:li it)))))) '(div ((class "content")) (ul ((class "items")) (li () "a") (li () "b") (li () "c")))
All expressions that don’t parse as an element are evaluated in place at runtime:
> (define (say-hi name) (format "Hi, ~a!" name))
> (haml (:h1 (say-hi "Bogdan"))) '(h1 () "Hi, Bogdan!")
Passing multiple elements to the haml macro produces a list of xexpr?s:
> (haml (:li "a") (:li "b")) '((li () "a") (li () "b"))