type less css in your sbt projects

a friendly css companion for coffeescripted-sbt using the less 1.4.2 embedded compiler via lesst.

For sbt 0.12 users

all(for less) # compiles all less source files regardless of freshness
less # compiles less source files
charset(for less) # character encoding used in file IO (defaults to utf-8)
mini(for less) # setting for compiled minification (false by default)
colors(for less) # setting for color error output (true by default)
lessCompiler(for less) # task for resolving the less compiler to compile .less sources
filter(for less) # filter for files included by the plugin
exclude-filter(for less) # filter for files ignored by the plugin
unmanaged-sources(for less) # lists resolved less sources
clean(for less) # deletes compiled css
config:source-directory(for less) # where less files will be resolved from
config:resource-managed(for less) # where compiled css will be copied to

For sbt 0.13 users, the syntax for accessing settings keys in the REPL slightly changed. setting keys are now camel cased from the REPL and less-scoped keys can be accessed when prefiexed with less::.

In your plugin definition, add

resolvers += Resolver.url(
  "bintray-sbt-plugin-releases",
    url("http://dl.bintray.com/content/sbt/sbt-plugin-releases"))(
      Resolver.ivyStylePatterns)
      
resolvers += "softprops-maven" at "http://dl.bintray.com/content/softprops/maven"

addSbtPlugin("me.lessis" % "less-sbt" % "0.2.2")

Then in your build definition, add

seq(lessSettings:_*)

This will append less-sbt's settings for the Compile and Test configurations.

To add them to other configurations, use the provided lessSettingsIn(config) method.

seq(lessSettingsIn(SomeOtherConfig):_*)

Author your .less files under your project's src/main/less directory. After compiling less sources, you can find the compiled css under path/to/resource_managed/main/css

Less css, itself, provides a built-in minifier which you can to to shink your compiled css. To override the default mini setting, add following to your build definition after including the less settings.

(LessKeys.mini in (Compile, LessKeys.less)) := true

To change the default location of compiled css files, add the following to your build definition

(resourceManaged in (Compile, LessKeys.less)) <<= (crossTarget in Compile)(_ / "your_preference" / "css")

Some lesscss projects, like Twitter's Bootstrap project contain one main .less file which imports multiple .less files using the @import feature of lesscss. To achieve the same style of compilation with less-sbt, set the filter defined by less-sbt to the target of compilation.

(LessKeys.filter in (Compile, LessKeys.less)) := "your_main.less"

This will build a single your_main.css file which includes all of the @imported style definitions.

To see an example of compiling Bootstrap itself, check out the scripted bootstrap test.

You will find all custom less-sbt keys within the LessKeys module.

Have an issue? Tell me about it

I'll take them where they make sense. Please use a feature branch in your fork, i.e. git checkout -b my-cool-feature, and if possible, write a scripted test for it.

Doug Tangren (softprops) 2011-2013