persistent data structures are implemented in ClojureScript. So they don't need to be ported for new compilation targets of ClojureScript like C in clojurec, I think.
Re:Clojure Obscura
by dustingetz on Thursday July 12, 2012 @06:03PM
(#4237100)
ClojureScript's core library has a dependency on Google Closure, and are optimized with knowledge of javascript vms. david nolen said that v8, for example, is blazingly fast at sequential instructions so they take great care to avoid function calls in critical paths.
here's some discussion that alludes to performance concerns in js vms: http://dev.clojure.org/jira/browse/CLJS-284
here's the original commit for PersistentVector, note how low level the code is: https://github.com/clojure/clojurescript/commit/e615f4cd326e...
here's more discusson by david nolen: https://groups.google.com/forum/?fromgroups#!searchin/clojur...
more discussion about allowing low level code access to js-specific special forms for numerics: https://groups.google.com/forum/?fromgroups#!searchin/clojur...
Lisps in general are appealing to implement. Clojure's core language is about as small as Scheme's, and there are a lot of Scheme implementations too. The parts of Clojure that set it apart from other Lisps (STM, persistent data structures) aren't always ported. I don't think any of the recent approaches to targeting C (Clj->Scheme->C, Clj->C) include STM or persistent data structures. I'd be happy to be pleasantly surprised though.