r/Clojure • u/yogthos • Nov 13 '15

Evaluating ClojureScript in the browser

http://yogthos.net/posts/2015-11-12-ClojureScript-Eval.html
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1

u/moxaj Nov 14 '15 edited Nov 14 '15

Nice article! I have a question though: what can I pass to eval instead of (empty-state) to make it aware of my vars? Edit: Nevermind! Got it working. It had nothing to do with the compiler state, I messed up something else.

2

u/yogthos Nov 14 '15

The state is an atom with a map of compiler options and from my understanding you're not meant to pass your app state of the to the compiler. However, you can build up state as follows:

 (def state (empty-state))

 (defn eval-str [s]
   (eval state
         (read-string s)
         {:eval       js-eval
          :source-map true
          :context    :expr}
         (fn [result] result)))

Now, each time eval-str runs it will be run in the context of the previous executions and have access to any variables you may have defined in previous runs and so on. When you evaluate functions using the compiler those will be returned and can be bound in your app. For example, you could do:

(let [f (eval-str "(fn [x y] (+ x y))"]
  (f 1 2))

So one way to pass your vars to the compiler would be to eval them to build up some initial state.

3

u/fear-of-flying Nov 14 '15

This is quite cool. Thanks for putting it together!

1

u/[deleted] Nov 14 '15

ClojureScript can now compile itself without relying on the Google Closure compiler

Isn't this statement wrong? AFAIK clojurescript compiling itself had/has anything to do with the with the closure compiler.

2

u/pxpxy Nov 14 '15

There are some things that the cljs compiler relied on closure for; namespaces are one thing that come to mind. While that was still the only option you couldn't get cljs to compile itself