# Lessons in the Fundamentals

09 March 2015

ClojureScript 0.0-3058 is a series of lessons in the fundamentals.

For the very first time ClojureScript ships with REPLs that deliver the functionality people have long ago come to expect from Clojure: :reload, :reload-all, doc, source, find-doc, apropos, dir, and pst are all there.

All REPLs ship with source mapping support enabled. Whether you’re in a REPL hooked up to Firefox, Safari, Chrome, Node.js, Rhino, or Nashorn you will always get a ClojureScript stacktrace.

## Compile Times

While slow compile times are acceptable for production builds, significantly slowing down the precious interactive programming feedback loop McCarthy gave us during development is simply unacceptable. ClojureScript now ships with aggressive caching features enabled including a pre-compiled standard library, pre-calculated analysis information, and pre-generated source map.

On my work machine I can now compile a trivial "Hello world!" from cold JVM boot in around 1.7 seconds.

## Utility Without Dependencies

My various “mies” Leiningen templates were patching over the fact that it was pretty much impossible to try ClojureScript without Leiningen or Maven to manage dependencies.

No more.

ClojureScript now provides a standalone JAR, the only thing you need to bring is an installation of Java 8.

## The Fundamentals

Even if you are an experienced ClojureScript developer it’s time to revisit the fundamentals.

I hope that through a shared understanding of the fundamentals we can collectively push the broader ClojureScript ecosystem of libraries and tooling to even greater heights.

Happy hacking!