cssgen

A clojure library to generate CSS code using an embedded domain-specific language (EDSL). In plain words: generate CSS files
by writing clojure code.

You can go here to read more about cssgen.

Please take a look at the upcoming syntax in version 0.3.0, tell me what you think: 0.3.0-SNAPSHOT

Using clojure instead of plain CSS you get a lot of benefices. You can use the full power of the language to do things
like:

• Define constants and use them in your rules

(def width (px 960))

• Operate with your constants using clojure expressions

(def main-width (* width 0.62))

• Define nested rules

(rule "a.plain"
:color :inherit
:text-decoration :inherit
:cursor :inherit
(rule "&:active, &:focus"
:outline :none)))

• Define reusable CSS snippets using plain old clojure functions and vars

(def has-layout
(mixin
; This makes ie6 get layout
:display "inline-block"
; and this puts it back to block
(rule "&" :display :block)))
(def clearfix
(mixin
:overflow :hidden
has-layout))

• Generate readable styles with better code organization

(rule "#nav"
(horizontal-list (px 9))
(rule "a"
(link-colors my-link-color my-visited-color my-hover-color)))

• Easy CSS ‘hacks’

(defn- float-side [side]
(mixin :display :inline :float side))
(defvar float-left (float-side :left)
"Implementation of float:left with fix for double-margin bug")
(defvar float-right (float-side :right)
"Implementation of float:right with fix for double-margin bug")
(rule "#secondary"
float-right)

Installation

The easiest way to install cssgen is by using Leiningen. Just add the following dependency to your project.clj file:

[cssgen "0.2.6"]

Usage

I’ll show some examples of use, but you should read the wiki for more details and information.

• CSS rules: to create a simple rule you use the rule function, passing the selector as first argument, and a
  series of property pairs.

(rule "ul.nav, ol"
:color :black
:background-color :#ddd
:padding [:1px "2px" (px 3) 0])

• Property values could be
  • keywords,
  • strings,
  • any other type convertible to string with as-str,
  • values sequences
  • special constructions like (px 9), (% 30), (col :#aaa) (more about this
    later).

If a property key must be associated with several values, you use a sequence of values, like in the padding
property above. Of course, if everything is “literal”, you could simply do :padding "1px 2px 3px 4px".

• You can nest rules:

(rule "#main, #secondary"
:padding "10px"
(rule "h1" ; this will generate a rule for "#main h1, #secondary h1"
:color :blue))

• If you need the parent selector on the nested rule, you can use “&” and it will get replaced:

(rule "a"
:color "#00C"
(rule "&:hover" ; this will generate a rule for a:hover
:color "#0CC"))

• You can define mixins with multiple rules and properties using functions or vars. Those can later be used in other
  definitions

(defn link-colors
([normal] (link-colors normal nil))
([normal hover]
(mixin
:color normal
(if visited (rule "&:visited" :color visited))
(if hover (rule "&:hover" :color hover)))))
(rule "a"
(link-colors "#00c" "#0cc"))

• As you can see in the previous example, nils in the properties list will be ignored:

• You can easily define constants

(def width (px 960))
(def h1-font-size (em 1.5))
(def h1-color (col :#0000ca))
(def h2-color (col :#0dd))
(def h3-color ($ :#0dd)) ; $ is just an alias for col
(def form-size (% 60))

• And use the basic arithmetic operations on them

(def main-width (* 0.7 width))
(def h2-font-size (- h1-font-size (em 0.3)))
(def h4-color (/ (+ h2-color h3-color) 2))

• To generate a new CSS file from the current clj code do:

(use 'cssgen.use)
(css-ns killerapp.css.screen
(:use (killerapp.css reset layout colors)))
(css-file "public/css/screen.css" ;this is the path to the target CSS file
.......
....... ; all your rules
.......)

Instead of css-ns you could use the normal (ns) call, but it gets a little tricky since we are redefining arithmetic
operations.

ToDo

• More syntactic sugar
• Helper functions to operate with colors and lengths
• Helpers to define dimensions and colors
• Methods to define rules without actually generating any CSS file
• Watcher to re-generate css files if source changed ???
• Property namespaces (font-*)
• Write a sass “compiler” to migrate from sass to cssgen
• Use that compiler to generate the whole compass tree in cssgen.
• Document
• Command line interface

Check the wiki for more usage information.

If you have a feature request, problem or comment, just drop me a line.