Welcome!

This is a collection of things you might need using Clojure—and how I resolve them.

§ Help, I forgot the Java/JS interop syntax—again!

§ I want to print a value inside a function call stack

Assume your code looks like this:

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(defn make-other-thing []
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  (produce-other-thing (filter-things-out (transform-thing-to-things (make-thing)))))

But now, you want to take a look at the result of transform-thing-to-things without interfering with the rest of the function.

This would be the naive approach:

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(defn make-other-thing []
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  (let [things (transform-thing-to-things (make-thing))]
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    (println things)
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    (produce-other-thing (filter-things-out things))))

But I think this is way better:

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(defn inspect [thing]
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  (println thing)
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  thing)
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(defn make-other-thing []
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  (produce-other-thing (filter-things-out (inspect (transform-thing-to-things (make-thing))))))

Or even:

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(defn inspect [thing]
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  (println thing)
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  thing)
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(defn make-other-thing []
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  (-> (make-thing)
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      transform-thing-to-things
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      inspect
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      filter-things-out
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      produce-other-thing))

And since inspect is a function that probably should’ve been in the standard library—we put it in our utils namespace:

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(ns example.utils.debug)
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(defn inspect [thing]
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  (println thing)
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  thing)

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(ns example.main
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  (:require
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    [example.utils.debug :refer [inspect]]))
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(defn make-other-thing []
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  (-> (make-thing)
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      transform-thing-to-things
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      inspect
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      filter-things-out
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      produce-other-thing))

§ ... not found on classpath. Help!

1. Check the spelling of the thing you want to include.
   1. Really check it.
   2. In every place.

If it’s not the spelling, it’s probably one of the following:

• The resource exists with the right name, but is not actually on the classpath.
  • Is it in the right folder? That is, with your :paths looking like this ({:paths ["src" "test" "resources"] ...}), is it in either ./src, ./test or./resources from the project root?
  • Did you add the folder to the classpath? ->

§ I struggle with creating the right namespace layout. Help!