#(into (empty %1) (distinct) (conj %1 %2)) is useful, I guess it’s not in core because when you need it it has bad algorithmic complexity

I guess it could be replaced with an insertion ordered set

is there a line counting program that counts number of functions? (something slightly more advanced than grepping for defn)

I guess def is both binding and assignment, because it implicitly wraps the value in a Var and assign the var a new value if called where a binding for the symbol already existed.

And I guess set! was made to not work on global vars because it wouldn't be atomic and could cause concurrency issues? So instead alter-var-root! was introduced as an atomic way to assign to the root of a global var?

And why wasn't set! used for atoms, when it is used for refs, agents and dynamic vars?

set! doesn't work with refs nor agents

(map list [:a :b :c] [:x :y :z :w])
;; or
(partition 2 (interleave [:a :b :c] [:x :y :z :w]))))
;; ?

vararg map-indexed

(map list (range) [:a :b :c] [:x :y :z :w])
=> ((0 :a :x) (1 :b :y) (2 :c :z))

to re-define a multmethod (the dispatch function), am I forced to ns-unmap first? If I do not the multimethod does not seem to be updated

@hmaurer I believe this is one of the cases where a redefine doesn't just work. Highly recommend using tools.namespace to reload your code.

@hmaurer there is remove-method

and remove-all-methods

If I have preconditions on a multimethod, where should I put them? On the dispatch function?

it depends, is it a precondition that underlies the multimethod itself, or is it specific to some dispatch?

Trying to port a third-party API to Clojure. API was originally written in C, vendor has packaged this as JNI, providing Java API. Vendor's java bin directory includes .jar, .dll, and .lib files. I am new to Clojure (longtime Common Lisper), have no real Java background. I got some help on #beginners a while back (https://clojurians-log.clojureverse.org/beginners/2017-08-05.html --- thanks, @noisesmith) but am still stuck. I haven't found a Clojure use case like this by Googling---just on Java-only JARs or on building a JNI from scratch and using that. I am using lein and CIDER on Windows. My defproject form now includes the following.

:jvm-opts ["-Djava.library.path=c:/NeticaJ_Win/NeticaJ_504/bin/"]
  :resource-paths ["c:/NeticaJ_Win/NeticaJ_504/bin/NeticaJ.jar"]

(:import [norsys.netica.Environ]
           []
           [norsys.neticaEx.aliases.Node])

edit-server.core> norsys.netica/Environ
CompilerException java.lang.ClassNotFoundException: norsys.netica, compiling:(*cider-repl edit-server*:1:7209) 
edit-server.core> (norsys.netica/Environ. nil)
ClassNotFoundException norsys.netica  java.net.URLClassLoader.findClass (URLClassLoader.java:381)

norsys.netica/Environ isn’t valid

it would be Environ with those imports

though norsys.netica.Environ is also allowed

Is it possible to have underscores for readability in numeric literals? E.g. 1_000_000

As far as I know Java has this, but clojure throws a number format exception.

it is not a valid number format for clojure

It’s really hard for me to read numbers like this 100000 especially when they get bigger.

Could I do something about it?

=> (long 1e+6)
1000000

though that means an extra conversion and if your not careful it might do the conversion at runtime instead of compile time

I can live with that, thank you.

there’s also 1e+6M which is a java.math.BigDecimal

@noisesmith That helps, thanks! Still a DLL issue, though:

edit-server.core> (norsys.netica.Environ. nil)
UnsatisfiedLinkError C:\NeticaJ_Win\NeticaJ_504\bin\NeticaJ.dll: Can't find dependent libraries  java.lang.ClassLoader$NativeLibrary.load (ClassLoader.java:-2)
edit-server.core> 

yeah, sounds like you need to fix your path for native libs, but that’s something I don’t have much experience with

do you have a sample java command line that is supposed to work with that lib?

Which of these would be more clojury and/or efficient? (into {} (map (fn [k] [(str k) {}]) some-seq)) or (zipmap (map str some-seq) (repeat {}))?

I'd prefer the latter, I think.

Or is there a third way that would be even better?

I was wondering, since the (zipmap (map ...) ...) appears to iterate twice over some-seq.

I tend to use juxt when I use (into {} ..) (into {} (map (juxt str (constantly {}))) some-seq)

Neat.

> (transduce (map str) (completing #(assoc! % %2 {}) persistent!) (transient {}) [1 2 3 4])
{"1" {}, "2" {}, "3" {}, "4" {}}

@noisesmith Vendor instructions to run demo are to run two batch files, in order, from demo directory. Contents follow. 1:

"C:\Program Files\Java\jdk1.8.0_131\bin\javac.exe" -deprecation -classpath ..\bin\NeticaJ.jar  *.java

set PATH=..\bin;%PATH%
   java  -classpath .;..\bin\NeticaJ.jar -Djava.library.path=..\bin  Demo

Does assoc-in have some dissoc-in counterpart?

that is the right translation, yes - you should be able to run the exact same commands except pointing to clojure.jar instead of the java files (plus a file running the clojure code you need)

@urzds no because there’s no consensus on what it would do if the key is already missing

(it’s discussed on Jira somewhere…)

@noisesmith Instead of using lein, defproject?

no no I’m saying using java - then when you find what works translate to lein

fundamentally, lein is a tool for managing java deps, so when your java deps are such that lein can’t manage them, you can skip lein.

java -classpath clojure.jar;..\binNeticaJ.jar;src -Djava.library.path=..\bin clojure.main some.clojure.ns

if src is the dir with your clojure code in it that is

(fix to point to the actual location of a clojure.jar, or copy a clojure.jar to the current ns)

Found the missing dissoc-in task in JIRA: https://dev.clojure.org/jira/browse/CLJ-1063

@noisesmith Thanks, will try.

@bschrag also you can leave off the namespace arg and just get a bare repl (no line editing and no namespaces pre-required though)

@noisesmith I gather that your some.clojure.ns plays the role of "script" in documentation from clojure.main --help: . For this, I might use my core.clj, including the ns form?

no, it’s a namespace arg to clojure.main - I think I forgot the -m that needs to go before that; so just a string is a file name, -m is the namespace to find and run (based on classpath) and -e is just code to eval

@bschrag btw this works

$ java -jar ~/bin/clojure.jar --help
Usage: java -cp clojure.jar clojure.main [init-opt*] [main-opt] [arg*]

  With no options or args, runs an interactive Read-Eval-Print Loop

  init options:
    -i, --init path     Load a file or resource
    -e, --eval string   Evaluate expressions in string; print non-nil values

  main options:
    -m, --main ns-name  Call the -main function from a namespace with args
    -r, --repl          Run a repl
    path                Run a script from a file or resource
    -                   Run a script from standard input
    -h, -?, --help      Print this help message and exit

  operation:

    - Establishes thread-local bindings for commonly set!-able vars
    - Enters the user namespace
    - Binds *command-line-args* to a seq of strings containing command line
      args that appear after any main option
    - Runs all init options in order
    - Calls a -main function or runs a repl or script if requested

  The init options may be repeated and mixed freely, but must appear before
  any main option. The appearance of any eval option before running a repl
  suppresses the usual repl greeting message: "Clojure ~(clojure-version)".

  Paths may be absolute or relative in the filesystem or relative to
  classpath. Classpath-relative paths have prefix of @ or @/

@noisesmith This works (!):

c:\NeticaJ_Win\NeticaJ_504\demo>java -classpath C:\Users\Schrag\.m2\repository\org\clojure\clojure\1.8.0\clojure-1.8.0.jar;c:\NeticaJ_Win\NeticaJ_504\bin\NeticaJ.jar -Djava.library.path=c:\NeticaJ_Win\NeticaJ_504\bin clojure.main
java -classpath C:\Users\Schrag\.m2\repository\org\clojure\clojure\1.8.0\clojure-1.8.0.jar;c:\NeticaJ_Win\NeticaJ_504\bin\NeticaJ.jar -Djava.library.path=c:\NeticaJ_Win\NeticaJ_504\bin clojure.main
Clojure 1.8.0
user=> (norsys.netica.Environ. nil)
#object[norsys.netica.Environ 0x6ca18a14 "norsys.netica.Environ@6ca18a14"]
user=> 

the string you give to classpath can go in :resource-paths and the -D… can go in :jvm-opts I think - you might need a ^:replace prefix on the jvm-opts value

but I bet there’s something more elegant that lets you leverage the maven ecosystem properly (I’m not super good at the library.path stuff though…)