A long time ago I used lein to create my project which I've been developing for several months. It created the files in the project which I just used as a template but didn't understand on day 1. How when I look at the main ns declaration, I wonder whether the form (:gen-class) needs to be removed. What purpose does it serve?

(ns clojure-rte.core
  (:require [clojure.set :refer [union]]
            [clojure.pprint :refer [cl-format]]
            [clojure-rte.cl-compat :refer [cl-cond]]
            [clojure-rte.util :refer [with-first-match call-with-collector
                                      fixed-point
                                      visit-permutations rte-constantly rte-identity
                                      partition-by-pred
                                      print-vals sort-operands member]]
            [clojure-rte.type :as ty]
            [clojure-rte.dfa :as dfa ]
            [clojure-rte.rte]
            [clojure-rte.memoize]
            [clojure-rte.api]
            [clojure-rte.type-extend]
            )
  (:gen-class))

if you don't aot compile, perhaps it is not necessary. this page might have some useful details: https://clojure.org/reference/compilation

does :gen-class simply allow me to define a function named -main which is then automatically called whenever the class is loaded?

No, it compiles a class with a static method named main (the - is the default prefix)

There is no automatic anything

When Java runs, it needs a class with a staric main to invoke

So :gen-class + a compile can give you a Java main entry point

Or you can just use clojure.main for the same purpose - it knows how to call the -main method on a Clojure ns (compiled or not)

what does a "Java main entry point" do? is that the function which is automatically run when java is started from the unix command line?

G'morning. Is there any way to add middleware to the nrepl that cursive sets up, when you choose the nrepl option for your repl configuration?