Learning to read and write recursively

Question

I am very new to Clojure and I have seen this template in other languages ​​before. I think I know how recursion works, but I don’t know how to read and how to think in such a way that this code can be written. Here's a trivial example:

(defn remove-dups [str]
  (when-let [[fst & rst] (seq str)]
    (if (= fst (first rst))
      (remove-dups rst)
      (cons fst (remove-dups rst)))))

I’m sure that an experienced Kladurorist doesn’t look very complicated. However, I still do not know how to read such code. Maybe there is a pattern that you should learn to understand? Lisp and Clojure are said to be reading “inside out,” but I can't find a quick way to mentally parse code like this. Maybe there is a way to "expand" recursive patterns by printing steps? Please, someone will teach me to think in terms of "divide and conquer."

Answer 1

I suspect this is a question that many people who want to get closer to Clojure ask themselves, and most of them are afraid to ask, so thanks for leaving. It is also a very personal commitment to wrap the brain around recursion. And I say this from expropriation. Back in college, I was a teacher in a course that introduced recursion (for five years), and I spend these five years trying to figure out a “way” to “show” people how to deploy code snippets like this.

During this time, I developed these ideas that seemed to hold on in every case:

• No one could read this code at the first exposure
• As soon as they “understood”, they could not then explain it in a useful way to those who had not yet “received”.
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Answer 2

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.

(defn remove-dups [str] (if (empty? str) nil (let [fst (first str) rst (rest str)] (if (= fst (first rst)) (remove-dups rst) (cons fst (remove-dups rst))))))

"" nil 3.