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For a key binding like this: ctrl-, f': 'chlorine:load-file' , just hit 'ctrl' then 'b' as usual ?


The suggested key bindings for Atom, it is actually a little weirder than that: ctrl-, means to hold down the Control key while typing the comma key. Let both go, then type f.


You can of course choose other key bindings if you wish, but might want to experiment with the suggested ones for a little while first and see if they grow on you or not.


Hey, it worked

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Is there an online Clojure forum ? I didn't see any on


There are and that I am aware of. There is a Clojure Google group, but I think a lot of the activity has moved away from there over the last several years to other places.


Clojureverse looks pretty good at first glance

Noah Bogart01:06:25

quick question: is there a way to make dissoc on a Record return a version of the record with nil as the value, instead of converting to a map?


Nothing built in that I am aware of. You can use assoc with a value of nil to do so.

Noah Bogart01:06:18

cool, that's what i thought


Whats up with REBL ? Yea or Nay ?


Sean Corfield has recorded a few screencasts recently to demonstrate one possible work flow that takes advantage of REBL. I know he really finds it productivity-enhancing, so I'm inclined to look further myself some time, hopefully soon.


Given my current lack of knowledge about it, I would say you don't need to learn to use it in order to learn Clojure, and there are plenty of things to learn other than that if you are new to the language, so don't feel you have to tackle that right from the start.


I agree. I don't want to get overwhelmed


Agreed. REBL is great once you have already internalized a REPL-driven workflow, and you want better visualization of results than the REPL can provide. Until you're at that point, don't worry about it.


deps-edn... deps is dependencies. what is edn ?


what is the purpose of

on a Symbol in function position? E.g.
(#'idx/index runtime LinkChild)
. I found that in a let here and am trying to grasp the implications: Lines 88, 97 and 107 in


its a reader macro that expands #'foo to (var foo)


this returns the var itself. ie. doesn't evaluate the passed in thing and return its value


why is it being used in that code? good question...


might be related to it being a test.

Alex Miller (Clojure team)12:06:31

Sometimes this is done to invoke private vars

Alex Miller (Clojure team)12:06:08

The symbol won’t resolve (because it’s private) but the var is always public

Alex Miller (Clojure team)12:06:02

And invoking a var that refers to a function will invoke the function

Felix Linker12:06:45

Peeps, I desperately need some help resolving a specific issue. I've written some code that generates a map. Like so:

(zipmap keys
        (map f keys))
Then, I not only wanted to map keys with f but also with g like so:
(zipmap keys
        (map (comp g f) keys))
However, exeuting that code in the REPL gives me:
Syntax error (NullPointerException) compiling at (form-init6822426521249811109.clj:1:8).
class clojure.lang.Compiler$CompilerException
Show: NoneClojureJavaToolingDuplicates	3707	clojure.lang.Compiler$InvokeExpr/eval	457	clojure.lang.Compiler$DefExpr/eval	7181	clojure.lang.Compiler/eval	7131	clojure.lang.Compiler/eval
core.clj:	3214	clojure.core/eval
core.clj:	3210	clojure.core/eval
main.clj:	414	clojure.main/repl/read-eval-print/fn
main.clj:	414	clojure.main/repl/read-eval-print
main.clj:	435	clojure.main/repl/fn
main.clj:	435	clojure.main/repl
main.clj:	345	clojure.main/repl	1523	clojure.lang.RestFn/invoke
interruptible_eval.clj:	79	nrepl.middleware.interruptible-eval/evaluate
interruptible_eval.clj:	55	nrepl.middleware.interruptible-eval/evaluate
interruptible_eval.clj:	142	nrepl.middleware.interruptible-eval/interruptible-eval/fn/fn	22	clojure.lang.AFn/run
session.clj:	171	nrepl.middleware.session/session-exec/main-loop/fn
session.clj:	170	nrepl.middleware.session/session-exec/main-loop	22	clojure.lang.AFn/run
nil:	-1	java.lang.Thread/run
What does that mean? I have no clue what to do. If I call g on some value of the map, that works out fine.

Felix Linker12:06:01

Ah! Got my first hint. Apparently, this issue comes from me wrapping said code execution in a (def v (call-to-my-f with-an-arg). If I just do (call-to-my-f with-an-arg) in the REPL, the exception becomes clearer :thinking_face:

Alex Miller (Clojure team)12:06:40

it's not obvious, but those are two different paths in the compiler

Alex Miller (Clojure team)12:06:16

(comp g f) == #(g (f %)) - were you expecting #(f (g %)) ?

Felix Linker12:06:19

No, that was alright. I just didn't know how to interpret that specific exception. And now I'm wondering why (def v (f x)) gives me a different exception than (f x) in the REPL.

Alex Miller (Clojure team)12:06:03

the former does an eval path while the latter will compile and then invoke. the exception handling is a little different. I'd be curious what the differences were. (there was actually a fix in this area in 1.10.1 so in particular wondering if you're on that)


@alexmiller Thanks! I will have to meditate on that 😉


My Clojure repo. looking for tips / advice / critiques ... on my structure, what to keep , what to ignore ...

Felix Linker23:06:28

You certainly should add *.DS_Store to your .gitignore to begin with.


The (:gen-class) expressions within the ns forms are only needed in fairly specific circumstances that you may not have encountered yet. I do not know if there are any circumstances where they can add confusing behavior, but certainly seems simpler to leave those out if you are not in a situation where it is necessary.


Your core.clj file contains a call to a function (hello-clojurians) that will cause that function to be called every time that file is loaded. Occasionally you do want such side effects just from loading a file, but again, maybe best to comment out that call in most situations.

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