Clojurians Log v2

Probably via cheshire. You can try to add-lib just cheshire and repro that way to exclude the bigger clj-kondo as a cause

hmm, no, can't repro with just cheshire

I see transit in the stack trace

can you repro with my steps above? just wondering if it's something specific to my setup

yes I can repro with just clj-kondo

perhaps try isolating using transit

not sure what's going on, but if there's anything I can do in clj-kondo let me know

well I can just use deps directly, but I get the impression that these 2 usages should result in the same output so wondering if there's some wrong or some caveats with add-lib

I can take a look at it. when you add libs, the lib versions you already have in scope are fixed, and it's possible you might need some newer version for the new lib you've added. there are definitely jackson lib versions that have compatibility issues due to breaking changes, would not surprise me at all if that's what you're seeing here.

to look at it, I need your starting deps.edn

it's all there in the setup, self contained

sorry, didn't scroll back far enough :)

I actually can't repro the CNFE

interesting

what version of the CLI are you using? clj -version

[I] filipesilva@Filipes-MacBook-Pro ~/s/repro-add-libs-clj-kondo (master) [SIGINT]> clj -version
Clojure CLI version 1.11.4.1474

I could repro it using:

$ clj --version
Clojure CLI version 1.11.4.1474

I'm using same, didn't fail for me

did you run from the project dir?

(just double checking)

yes

I have stuff in ~/.clojure/deps.edn but just tried with -Srepro to ignore it and could still get the CNFE:

[I] filipesilva@Filipes-MacBook-Pro ~/s/repro-add-libs-clj-kondo (master) [SIGINT]> clj -Srepro
Clojure 1.12.0-rc2
user=> (add-lib 'clj-kondo/clj-kondo {:mvn/version "2024.08.29"})
[babashka/fs borkdude/edamame borkdude/sci.impl.reflector cheshire/cheshire clj-kondo/clj-kondo com.cognitect/http-client com.fasterxml.jackson.core/jackson-core com.fasterxml.jackson.dataformat/jackson-dataformat-cbor com.fasterxml.jackson.dataformat/jackson-dataformat-smile com.github.javaparser/javaparser-core io.replikativ/datalog-parser nrepl/bencode org.babashka/sci org.babashka/sci.impl.types org.eclipse.jetty/jetty-client org.eclipse.jetty/jetty-http org.eclipse.jetty/jetty-io org.eclipse.jetty/jetty-util tigris/tigris]
user=> (require '[clj-kondo.core :as clj-kondo])
nil
user=> (nil? (clj-kondo/run! {:lint ["src"] :config {:analysis true}}))
Execution error (ClassNotFoundException) at jdk.internal.loader.BuiltinClassLoader/loadClass (BuiltinClassLoader.java:641).
com.fasterxml.jackson.core.JsonFactory

I'm on mac, in case it matters

I see a different set of deps loaded by add-lib (the return value)

in case it matters:

$ java --version
java 21.0.3 2024-04-16 LTS
Java(TM) SE Runtime Environment Oracle GraalVM 21.0.3+7.1 (build 21.0.3+7-LTS-jvmci-23.1-b37)
Java HotSpot(TM) 64-Bit Server VM Oracle GraalVM 21.0.3+7.1 (build 21.0.3+7-LTS-jvmci-23.1-b37, mixed mode, sharing)

can you give me your clj -Srepro -Stree output

$ clj -Srepro -Stree
org.clojure/clojure 1.12.0-rc2
  . org.clojure/spec.alpha 0.5.238
  . org.clojure/core.specs.alpha 0.4.74
com.datomic/local 1.0.285
  . com.datomic/client 1.0.138
    . com.cognitect/anomalies 0.1.12
    . com.datomic/client-api 1.0.69
    . com.datomic/client-impl-shared 1.0.106
      . com.cognitect/hmac-authn 0.1.211
        . commons-codec/commons-codec 1.16.0
        . com.cognitect/anomalies 0.1.12
        . org.clojure/core.async 1.6.681
      X com.cognitect/http-client 1.0.127 :excluded
      . com.cognitect/transit-clj 1.0.333
        . com.cognitect/transit-java 1.0.371
          X com.fasterxml.jackson.core/jackson-core 2.14.2 :excluded
          . org.msgpack/msgpack 0.6.12
            . com.googlecode.json-simple/json-simple 1.1.1
            . org.javassist/javassist 3.18.1-GA
          . javax.xml.bind/jaxb-api 2.4.0-b180830.0359
            . javax.activation/javax.activation-api 1.2.0
    . com.datomic/query-support 0.8.28
    . org.clojure/core.async 1.6.681
  . com.cognitect/anomalies 0.1.12
  . com.datomic/query-support 0.8.28
  . org.clojure/core.async 1.6.681
    . org.clojure/tools.analyzer.jvm 1.2.3
  . org.clojure/tools.analyzer.jvm 1.2.3
    . org.clojure/tools.analyzer 1.1.1
    . org.clojure/core.memoize 1.0.253
    . org.ow2.asm/asm 9.2
    . org.clojure/tools.reader 1.3.6
  . org.clojure/tools.analyzer 1.1.1
  . org.clojure/core.memoize 1.0.253
    . org.clojure/core.cache 1.0.225
  . org.clojure/core.cache 1.0.225
    . org.clojure/data.priority-map 1.1.0
  . org.clojure/data.priority-map 1.1.0
  . org.ow2.asm/asm 9.2
  . org.clojure/tools.reader 1.3.6
  X org.clojure/spec.alpha 0.2.176 :older-version
  X org.clojure/core.specs.alpha 0.2.44 :older-version
  . com.datomic/client-impl-shared 1.0.106
    . com.cognitect/anomalies 0.1.12
    . org.clojure/core.async 1.6.681
  . commons-io/commons-io 2.15.1
  . com.datomic/query-stats 1.0.12
  . org.fressian/fressian 0.6.8
  . com.github.ben-manes.caffeine/caffeine 2.8.1
    . org.checkerframework/checker-qual 3.1.0
    . com.google.errorprone/error_prone_annotations 2.3.4
  . org.checkerframework/checker-qual 3.1.0
  . com.google.errorprone/error_prone_annotations 2.3.4
  . com.datomic/io-stats 1.0.12
  . com.datomic/client-api 1.0.69
    . org.clojure/core.async 1.6.681

org.clojure/clojure 1.12.0-rc2
  . org.clojure/spec.alpha 0.5.238
  . org.clojure/core.specs.alpha 0.4.74
com.datomic/local 1.0.285
  . com.datomic/client 1.0.138
    . com.cognitect/anomalies 0.1.12
    . com.datomic/client-api 1.0.69
    . com.datomic/client-impl-shared 1.0.106
      . com.cognitect/hmac-authn 0.1.211
        . commons-codec/commons-codec 1.16.0
        . com.cognitect/anomalies 0.1.12
        . org.clojure/core.async 1.6.681
      X com.cognitect/http-client 1.0.127 :excluded
      . com.cognitect/transit-clj 1.0.333
        . com.cognitect/transit-java 1.0.371
          X com.fasterxml.jackson.core/jackson-core 2.14.2 :excluded
          . org.msgpack/msgpack 0.6.12
            . com.googlecode.json-simple/json-simple 1.1.1
            . org.javassist/javassist 3.18.1-GA
          . javax.xml.bind/jaxb-api 2.4.0-b180830.0359
            . javax.activation/javax.activation-api 1.2.0
    . com.datomic/query-support 0.8.28
    . org.clojure/core.async 1.6.681
  . com.cognitect/anomalies 0.1.12
  . com.datomic/query-support 0.8.28
  . org.clojure/core.async 1.6.681
    . org.clojure/tools.analyzer.jvm 1.2.3
  . org.clojure/tools.analyzer.jvm 1.2.3
    . org.clojure/tools.analyzer 1.1.1
    . org.clojure/core.memoize 1.0.253
    . org.ow2.asm/asm 9.2
    . org.clojure/tools.reader 1.3.6
  . org.clojure/tools.analyzer 1.1.1
  . org.clojure/core.memoize 1.0.253
    . org.clojure/core.cache 1.0.225
  . org.clojure/core.cache 1.0.225
    . org.clojure/data.priority-map 1.1.0
  . org.clojure/data.priority-map 1.1.0
  . org.ow2.asm/asm 9.2
  . org.clojure/tools.reader 1.3.6
  X org.clojure/spec.alpha 0.2.176 :older-version
  X org.clojure/core.specs.alpha 0.2.44 :older-version
  . com.datomic/client-impl-shared 1.0.106
    . com.cognitect/anomalies 0.1.12
    . org.clojure/core.async 1.6.681
  . commons-io/commons-io 2.15.1
  . com.datomic/query-stats 1.0.12
  . org.fressian/fressian 0.6.8
  . com.github.ben-manes.caffeine/caffeine 2.8.1
    . org.checkerframework/checker-qual 3.1.0
    . com.google.errorprone/error_prone_annotations 2.3.4
  . org.checkerframework/checker-qual 3.1.0
  . com.google.errorprone/error_prone_annotations 2.3.4
  . com.datomic/io-stats 1.0.12
  . com.datomic/client-api 1.0.69
    . org.clojure/core.async 1.6.681

hah:

X com.fasterxml.jackson.core/jackson-core 2.14.2 :excluded

> I see a different set of deps loaded by add-lib (the return value) I see a different set depending on wether I use -Srepro but thats to be expected

is it? you have :deps in ~/.clojure/deps.edn ?

yes, I do:

:deps {;; 
        criterium/criterium         {:mvn/version "0.4.6"}
        ;; 
        ;; remember to do `(require 'hashp.core)`
        hashp/hashp                 {:mvn/version "0.2.2"}
        ;; 
        vvvvalvalval/scope-capture  {:mvn/version "0.3.3"}
        ;; 
        org.clojure/tools.trace     {:mvn/version "0.8.0"}
        ;; 
        io.github.tonsky/clj-reload {:mvn/version "0.4.1"}
        ;; 
        datascript/datascript {:mvn/version "1.6.5"}
        }

perhaps move them to a :dev alias or so. having deps in deps.edn can cause unexpected issues since those deps are always prioritized over whatever you have in your project

in the case of this repro I think -Srepro should ignore them, right?

yes

(but I agree that you should put them in an alias :)

I do have clojure itself in the the deps there, since I want to force myyself to use clojure 1.12 rc2 everywhere ;)

I cannot now see what I thought was different in my output, so I may just need more coffee

oh, I was comparing to your first output without -Srepro, but I match the later one

but I still don't get the CNFE

is there anything else that could be affecting the repro?

nothing coming to mind yet. stepping away for a meeting

I definitely have the class

I can repro inside a clojure docker container, for a clean env

[I] filipesilva@Filipes-MacBook-Pro ~/s/repro-add-libs-clj-kondo (master) [SIGINT]> docker run -it --rm clojure sh


# ll
sh: 1: ll: not found
# ls
clojure-2257487035549979519.edn  hsperfdata_root  target
# which clj
/usr/local/bin/clj
# mkdir -p repro-add-libs-clj-kondo/src
# cd repro-add-libs-clj-kondo
# echo '{:paths ["src"] :deps {org.clojure/clojure {:mvn/version "1.12.0-rc2"} com.datomic/local {:mvn/version "1.0.285"}}}' > deps.edn
# echo '(ns user)' > src/user.clj
# clj

Downloading: com/datomic/local/1.0.285/local-1.0.285.pom from central
 .... elided a lot of stuff ....
Downloading: org/clojure/core.async/1.6.681/core.async-1.6.681.jar from central
Clojure 1.12.0-rc2
user=> (add-lib 'clj-kondo/clj-kondo {:mvn/version "2024.08.29"})
[babashka/fs borkdude/edamame borkdude/sci.impl.reflector cheshire/cheshire clj-kondo/clj-kondo com.cognitect/http-client com.fasterxml.jackson.core/jackson-core com.fasterxml.jackson.dataformat/jackson-dataformat-cbor com.fasterxml.jackson.dataformat/jackson-dataformat-smile com.github.javaparser/javaparser-core io.replikativ/datalog-parser nrepl/bencode org.babashka/sci org.babashka/sci.impl.types org.eclipse.jetty/jetty-client org.eclipse.jetty/jetty-http org.eclipse.jetty/jetty-io org.eclipse.jetty/jetty-util tigris/tigris]
user=> (require '[clj-kondo.core :as clj-kondo])
nil
user=> (nil? (clj-kondo/run! {:lint ["src"] :config {:analysis true}}))
Execution error (ClassNotFoundException) at jdk.internal.loader.BuiltinClassLoader/loadClass (BuiltinClassLoader.java:641).
com.fasterxml.jackson.core.JsonFactory
user=>
# ^C
# ^C
# exit
[I] filipesilva@Filipes-MacBook-Pro ~/s/repro-add-libs-clj-kondo (master) [SIGINT]>

when you get to this point, can you do com.fasterxml.jackson.core.JsonFactory to find the class, or not?

wondering if it is a timing thing with loading

huh that's interesting

[N] filipesilva@Filipes-MacBook-Pro ~/s/repro-add-libs-clj-kondo (master) [SIGINT]> clj -Srepro
Clojure 1.12.0-rc2
user=> (add-lib 'clj-kondo/clj-kondo {:mvn/version "2024.08.29"})
[babashka/fs borkdude/edamame borkdude/sci.impl.reflector cheshire/cheshire clj-kondo/clj-kondo com.cognitect/http-client com.fasterxml.jackson.core/jackson-core com.fasterxml.jackson.dataformat/jackson-dataformat-cbor com.fasterxml.jackson.dataformat/jackson-dataformat-smile com.github.javaparser/javaparser-core io.replikativ/datalog-parser nrepl/bencode org.babashka/sci org.babashka/sci.impl.types org.eclipse.jetty/jetty-client org.eclipse.jetty/jetty-http org.eclipse.jetty/jetty-io org.eclipse.jetty/jetty-util tigris/tigris]
user=> (require '[clj-kondo.core :as clj-kondo])
nil
user=> (nil? (clj-kondo/run! {:lint ["src"] :config {:analysis true}}))
Execution error (ClassNotFoundException) at jdk.internal.loader.BuiltinClassLoader/loadClass (BuiltinClassLoader.java:641).
com.fasterxml.jackson.core.JsonFactory
user=> (nil? (clj-kondo/run! {:lint ["src"] :config {:analysis true}}))
Execution error (ClassNotFoundException) at com.cognitect.transit.impl.ReaderFactory$JsonReaderImpl/createParser (ReaderFactory.java:150).
com.fasterxml.jackson.core.JsonFactory
user=> com.fasterxml.jackson.core.JsonFactory
com.fasterxml.jackson.core.JsonFactory
user=> (type com.fasterxml.jackson.core.JsonFactory)
java.lang.Class
user=> (nil? (clj-kondo/run! {:lint ["src"] :config {:analysis true}}))
Execution error (ClassNotFoundException) at com.cognitect.transit.impl.ReaderFactory$JsonReaderImpl/createParser (ReaderFactory.java:150).
com.fasterxml.jackson.core.JsonFactory
user=>

look at how the error changes on the second time I call clj-kondo/run!

the class is there

can even call type on it, but clj-kondo still throws CNFE

what happens when you now do (require 'clj-kondo.core :reload-all) ? just a wild guess

something to do with kondo caching?

I just confirmed that sequence above: I got the same error Filipe got, but was able to type the classname, and then got a different error regarding that classname on retrying the clj-kondo/run! call per Filipe's REPL session.

(For me, that's on Ubuntu 20.04, WSL2, Windows)

can you also check what you get for this?

user=> (.getResource (.getContextClassLoader (Thread/currentThread)) "com/fasterxml/jackson/core/JsonFactory.class")
#object[java.net.URL 0x131fcb6f "jar:file:/Users/alex.miller/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.17.0/jackson-core-2.17.0.jar!/com/fasterxml/jackson/core/JsonFactory.class"]

that is, is the class in jackson-core jar?

user=> (.getResource (.getContextClassLoader (Thread/currentThread)) "com/fasterxml/jackson/core/JsonFactory.class")
#object[java.net.URL 0x18af5091 "jar:file:/home/sean/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.17.0/jackson-core-2.17.0.jar!/com/fasterxml/jackson/core/JsonFactory.class"]

Is something in Kondo (or Transit) using its own class loader perhaps?

also, can someone drop the (pst *e) when you get the CNFE?

The first one or the second one? Or both?

both I guess (unless they're the same :)

transit is not doing anything special with classloaders as far as I recall

user=> (nil? (clj-kondo/run! {:lint ["src"] :config {:analysis true}}))
Execution error (ClassNotFoundException) at jdk.internal.loader.BuiltinClassLoader/loadClass (BuiltinClassLoader.java:641).
com.fasterxml.jackson.core.JsonFactory
user=> (pst *e)
RuntimeException java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonFactory
	com.cognitect.transit.impl.ReaderFactory$JsonReaderImpl.createParser (ReaderFactory.java:154)
	com.cognitect.transit.impl.ReaderFactory$ReaderImpl.initialize (ReaderFactory.java:134)
	com.cognitect.transit.impl.ReaderFactory$ReaderImpl.read (ReaderFactory.java:110)
	cognitect.transit/read (transit.clj:323)
	cognitect.transit/read (transit.clj:319)
	clj-kondo.impl.cache/from-cache-1/fn--4219 (cache.clj:32)
	clj-kondo.impl.cache/from-cache-1 (cache.clj:31)
	clj-kondo.impl.cache/from-cache-1 (cache.clj:20)
	clj-kondo.impl.cache/load-when-missing (cache.clj:115)
	clj-kondo.impl.cache/load-when-missing (cache.clj:108)
	clj-kondo.impl.cache/sync-cache*/fn--4276/fn--4277/fn--4278 (cache.clj:161)
	clojure.core.protocols/iterator-reduce! (protocols.clj:42)
Caused by:
NoClassDefFoundError com/fasterxml/jackson/core/JsonFactory
	com.cognitect.transit.impl.ReaderFactory$JsonReaderImpl.createParser (ReaderFactory.java:150)
	com.cognitect.transit.impl.ReaderFactory$ReaderImpl.initialize (ReaderFactory.java:134)
Caused by:
ClassNotFoundException com.fasterxml.jackson.core.JsonFactory
	jdk.internal.loader.BuiltinClassLoader.loadClass (BuiltinClassLoader.java:641)
	jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass (ClassLoaders.java:188)
nil
user=> (nil? (clj-kondo/run! {:lint ["src"] :config {:analysis true}}))
Execution error (ClassNotFoundException) at com.cognitect.transit.impl.ReaderFactory$JsonReaderImpl/createParser (ReaderFactory.java:150).
com.fasterxml.jackson.core.JsonFactory
user=> (pst *e)
RuntimeException java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonFactory
	com.cognitect.transit.impl.ReaderFactory$JsonReaderImpl.createParser (ReaderFactory.java:154)
	com.cognitect.transit.impl.ReaderFactory$ReaderImpl.initialize (ReaderFactory.java:134)
	com.cognitect.transit.impl.ReaderFactory$ReaderImpl.read (ReaderFactory.java:110)
	cognitect.transit/read (transit.clj:323)
	cognitect.transit/read (transit.clj:319)
	clj-kondo.impl.cache/from-cache-1/fn--4219 (cache.clj:32)
	clj-kondo.impl.cache/from-cache-1 (cache.clj:31)
	clj-kondo.impl.cache/from-cache-1 (cache.clj:20)
	clj-kondo.impl.cache/load-when-missing (cache.clj:115)
	clj-kondo.impl.cache/load-when-missing (cache.clj:108)
	clj-kondo.impl.cache/sync-cache*/fn--4276/fn--4277/fn--4278 (cache.clj:161)
	clojure.core.protocols/iterator-reduce! (protocols.clj:42)
Caused by:
NoClassDefFoundError com/fasterxml/jackson/core/JsonFactory
	com.cognitect.transit.impl.ReaderFactory$JsonReaderImpl.createParser (ReaderFactory.java:150)
	com.cognitect.transit.impl.ReaderFactory$ReaderImpl.initialize (ReaderFactory.java:134)
Caused by:
ClassNotFoundException com.fasterxml.jackson.core.JsonFactory
	com.cognitect.transit.impl.ReaderFactory$JsonReaderImpl.createParser (ReaderFactory.java:150)
	com.cognitect.transit.impl.ReaderFactory$ReaderImpl.initialize (ReaderFactory.java:134)
nil
user=>

Yup, seeing the same here.

you might see difference from 1st to 2nd based on changing negative cache info in the classloaders themselves

but I suspect the real problem here is the classloader being used during the read from from the transit cache not reaching the dynamic classloader where the classes have been added

any hypothesis on why it doesn't repro on your setup?

no

exciting then 😄

did you try the docker repro?

I assume it will repro, but what does that buy me

if that one doesn't repro for you it's even more weird... then it's not about the contents of the system, but maybe about the physical characteristics

but I don't have any interesting conclusion from that either

I don't actually have docker installed on this computer, don't really want to do so atm

afaict I have no clj-kondo caches anywhere in my tree, is that also true for yall?

I don't see what this has to do with the above problem. clj-kondo always reads its bundled cache anyways (transit) so even if you don't have a cache on disk, stuff is being read

and in a clean docker repro it also occurs

same, no clj kondo cache

interesting data point: starting with clj-kondo and adding datomic-local via add-lib does not throw CNFE:

[I] filipesilva@Filipes-MacBook-Pro ~/s/repro-add-libs-clj-kondo (master)> echo '{:paths ["src"] :deps {org.clojure/clojure {:mvn/version "1.12.0-rc2"} clj-kondo/clj-kondo {:mvn/version "2024.08.29"}}}' > deps.edn
[I] filipesilva@Filipes-MacBook-Pro ~/s/repro-add-libs-clj-kondo (master) [SIGINT]> clj -Srepro
Clojure 1.12.0-rc2
user=> (require '[clj-kondo.core :as clj-kondo])
nil
user=> (nil? (clj-kondo/run! {:lint ["src"] :config {:analysis true}}))
false
user=> (add-lib 'com.datomic/local {:mvn/version "1.0.285"})
[com.cognitect/anomalies com.cognitect/hmac-authn com.datomic/client com.datomic/client-api com.datomic/client-impl-shared com.datomic/io-stats com.datomic/local com.datomic/query-stats com.datomic/query-support com.github.ben-manes.caffeine/caffeine com.google.errorprone/error_prone_annotations commons-codec/commons-codec commons-io/commons-io org.checkerframework/checker-qual org.clojure/core.async org.clojure/core.cache org.clojure/core.memoize org.clojure/data.priority-map org.clojure/tools.analyzer org.clojure/tools.analyzer.jvm org.fressian/fressian]
user=> (require '[datomic.client.api :as d])
nil
user=> (def client (d/client {:server-type :datomic-local :storage-dir "/tmp/repro" :system "mem"}))
#'user/client
user=> (d/create-database client {:db-name "repro"})
true

Can you compare (:libs (clojure.java.basis/current-basis)) from those two paths

sorry what paths?

like, before and after adding clj-kondo in the original repro?

Yeah, basic at so you end up at the same place

that's starting with datomic, before adding clj-kondo, after adding clj-kondo

I guess better than libs you could check :classpath-roots

and that's starting with clj-kondo, adding datomic

That’s the only thing with cp ordering, not sure if that matters

ok gonna do it again but with classpath-roots

starting with datomic, add clj-kondo

start with clj-kondo, add datomic-local

starting with both datomic-local and clj-kondo on deps.edn

FWIW I was able to roughly double the performance again with the following approach: Create a static hashmap containing all the static key-vals, and in the case of static-key+dynamic-val, set the value to a sentinel object containing the index that the value will be at when called to create an instance of the map. This allows the hashmap instances to share as much structure as possible with the static "template"

Perhaps the more generic way to do this would be to make an optimized update-vals implementation which takes advantage of the HashMap structure, directly cloning each node and swapping out the value with (f value) rather (assoc! acc k (f v)) each element as it currently does. Then you could I guess use a more simplified approach than the above. The "Original" could store the index of the value in the literal expression, and then when creating instances, swap out the index value for the value at the index. Something like:

(let [original {:a 0 :b 1 :c 2 :d 3 :e 4}]
      values [(foo) (foo) (foo) (foo) (foo)]
  (update-vals original (fn [i] (nth values i))))

(actual implementation would be Java but you get the idea)

you should see my talk from JVMLS a few years ago, I talk about templates directly

Oh nice, link?

https://youtu.be/UbqNrZMbxBg?t=2188

Very nice, thanks for that

Did a quick implementation, seems quite promising, like 400% speedup in the case of 10 keys

400% speedup... on 0.001% of runtime

Hehe yes. Not sure if there's an easy way to get an idea of how much time/memory is being spent intializing these maps in typical clojure programs

Pushed the prototype implementation up if people wanted to see https://github.com/joshlemer/clojure/pull/1/files?diff=split&w=1