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

Question

Clojure beginner here.

I've created a leiningen project "adventofcode" and I've created a file "src/adventofcode/2024/day7.clj" with this namespace:

(ns adventofcode.2024.day7
  (:gen-class)
  (:require
    [clojure.math]
    [clojure.math.combinatorics]
    [clojure.pprint]))

Now when I run lein repl the prompt is adventofcode.core. How can I call a function in the file above? Or switch to the namespace adventofcode.2024? Tab completion suggests that this namespace doesn't exist. Do I manually have to load the file somehow?

I'm just starting out. If I'm making my life unnecessarily hard with this project structure I wouldn't mind a comment on that too.

Answer 1

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.

Comments

Unfortunately, that didn't work: [adventofcode.2024.day7 :as day7] ->
Syntax error (ClassNotFoundException) compiling at (/tmp/form-init6149621435280713369.clj:1:8977).
adventofcode.2024.day7

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I tried to rename 2024 to test. Both the namespace in day7.clj as well as the directory the file is in. Unfortunately yielding the same result.

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Do you have a minimal reproducible example?

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My MRE: https://github.com/cyberdynesoftware/howto-lein-repl

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Add `(:require [howto-lein-repl.test.callme :as callme])` to the `ns` form in the `core` namespace, add `(callme/f)` at the end of the `-main` function, start `lein repl`, execute `(-main)`.

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Ok, this works. "success" is printed. However, what I actually wanted to do is to call f directly at the repl. Is this not possible? Can I only call functions in another file / namespace through a proxy function in core?

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After adding the `:require` form, have you tried restarting the REPL (or reloading the `core` namespace properly) and running `(callme/f)`? Works for me.

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Yes, that works. Thank you. Is it possible to call f without requiring the namespace in core? Thus can I somehow require the callme namespace directly at the repl?

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You can use `(require '[howto-lein-repl.test.callme :as callme])` for that. Every key in the `ns` form has a macro alternative.

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Thank you very much for your help.