Clojure Q&A - Recent questions and answers in Beginner

Answered: Trying to extract vec from vec - conj not working?

Mon, 15 Dec 2025 04:02:15 +0000

Thanks Harold. I see.

For others coming here Harolds comment above is the answer (I don't know how to select it as the answer directly).

Answered: Can you help me choosing a book?

Tue, 26 Aug 2025 16:54:53 +0000

Yes, that's still a fine choice, even though some things have been added since it was written.

See https://clojure.org/guides/getting_started#_how_do_i_learn_the_language for some more resources.

Answered: How to call a function in another ns in lein repl?

Sun, 12 Jan 2025 09:37:58 +0000

Using adventofcode.2024.day7, you have to require it as adventofcode.2024.day7, not as adventofcode.2024. Tab completion might not work properly because the middle part of the namespace is a number, but I'm not sure - in any case, don't rely on tab-completion alone.

So, suppose you have a function f in that namespace. Require it as [adventofcode.2024.day7 :as day7] or with some other alias that you prefer, and call f from adventofcode.core as (day7/f), that's it.

The only problem with that naming is if you decide to use the generated classes from Java-the-language. It doesn't support numeric package segments, even though JVM does support them.

Answered: Is learning java necessary before diving into clojure?

Wed, 25 Dec 2024 10:05:10 +0000

I've been advised that learning Java is necessary before diving into Clojure.

That was a bad advice. Learning Java would be helpful, but it's not necessary. And if you end up needing some Java, 95% of the time you need to know just the syntax, the behavior, and the specific functionality that you need - not the whole suite of things that Java offers in its standard library.

Java is vast and verbose, and mastering it can take years, not just a few months.

There's Java-the-language and there's its standard library. The first is not an ocean by any means - it's still larger than Clojure, but is definitely doable. You can get comfortable with all its main features in under a week.
And the standard library - just search online for a specific thing you need to do, when you need to do it. Knowing everything in advance would be helpful, but learning everything in advance is likely to be a waste of time.

Is it possible to effectively learn Clojure without a deep understanding of Java? Any tips or resources to achieve this?

I used the official reference, docstrings, the source code, and examples at https://clojuredocs.org/. Someone else would use books, tutoring, videos, etc. - it depends on what you prefer.

The first time I used Clojure in any serious capacity was to implement a take-home task at a job I was applying to. Ironically, the job was in Java and I didn't know Java, but they accepted solutions in any language. I haven't read or written a line in Java or even about Java in order to implement that task and get accepted.