1) IReduce protocol is missing implementation for array and List.
2) append! uses (.add array), while the correct array method name is push

Patch attached.

Note: what is your experience with array.push performance? ClojureScript reducers/foldcat uses arrays for append! / cat implementation. My experience was that (into [] ...) using conj! and TransientVector was at least 5 times faster than reducers/foldcat using array and push. The reason is probably inefficient push implementation in Chrome/V8

Put together an easy to run series of persistent data structure benchmarks that can be easily run. For example we would like to submit to this Mozilla ticket http://bugzilla.mozilla.org/show_bug.cgi?id=874174

Here are some benchmarks after performance improvements have been applied to PersistentArrayMap in master:

• ObjMap vs PersistentArrayMap 1 entry -lookup, http://jsperf.com/ojbmap-vs-persistentarraymap-lookup-1
• ObjMap vs PersistentArrayMap 3 entry -lookup, http://jsperf.com/objectmap-vs-persistentarraymap-3-lookup
• ObjMap vs PersistentArrayMap 7 entry -lookup, http://jsperf.com/objmap-vs-persistentarraymap-7-lookup

For the smallest sizes PAMs are nearly identical in performance to OMs, as we start nearing the PHM threshold PAMs are nearly 2X faster on WebKit Nightly, and nearly 3X faster on the latest Chrome. Only Firefox Nightly lags behind for lookup times at larger sizes.

• ObjMap vs PersistentArrayMap assoc empty, http://jsperf.com/objmap-vs-persistentarraymap-assoc-empty
• ObjMap vs PersistentArrayMap assoc 3kv, http://jsperf.com/objmap-vs-persistentarraymap-assoc-3
• ObjMap vs PersistentArrayMap assoc 7kv, http://jsperf.com/objmap-vs-persistentarraymap-assoc-7kv

Again we see nearly identical (or much better) performance at small sizes and much better performance for PAMs as we approach the PHM threshold.

Problem:
Some code has different semantics when compiled in advanced mode.
Clojurescript tries to minimize those cases, but examples are usage of aget or forgotten externs files.
There exits closure compiler options to generate names based on original expressions, even with advanced optimizations.
However, there exists no clojurescript compiler option for that.

Proposal:
Add a :debug compiler option to clojurescript, which can be set to true to turn the following closure compiler options on:

• generatePseudoNames true
• anonymousFunctionNaming AnonymousFunctionNamingPolicy/UNMAPPED

Attached patch implements this, as a result the compiled test suite is indeed quite readable.

It looks like *cljs-data-readers* is not being bound to *data-readers* where it should be.

At a minimum, cljs.repl/load-stream does not. The practical effect of this instance is that e.g. (load-file "some/cljs/file.cljs") will fail if that file or any other contains a user-defined literal tag. Similar behaviour exists elsewhere, e.g. (load-namespace 'some.cljs.ns) will not load a namespace that contains user-defined tags (I think that one is due to *cljs-data-readers* not being bound in the analyzer).

This is related to CLJS-479 insofar as it's another symptom of ClojureScript loading code in subtly different ways in multiple places.

I'm happy to do either of:

1. submit issues+patches fixing issues as I encounter them, or
2. attempt a more significant refactoring that sets up (hopefully) one and only one place where ClojureScript reads code (i.e. uses LispReader) so that behaviour can be consistent

I'm somewhat hesitant re: (2) insofar as the specific requirements of the compiler and analyzer and REPL may be divergent in ways that I'm not yet aware of, but it seems like it's worth a shot.