Clojure：在特定命名空间中启动repl

Question

I have boot-clj installed and want to be able to edit a .clj file in an external editor and separately have a command line REPL running from which I can call the functions that I change in the .clj file. No special reloading commands should be required.

Another thing is I don't want to have to manually type commands to include namespaces - I would like to just run a script that brings me into the namespace, so I can call existing functions right away.

Name of the file:

C:\dev\my-project\src\my_project\utils.clj

Something of what is inside the file:

(ns my-project.utils
  (:require
    [clojure.string :as s]))

(defn my-range [start end]
  (take (- end start) (iterate inc start)))

I would like to go straight into a REPL and go (my-range 0 3) and see if it produces the result I want.

What's the setup for this? What would the script file I need to run look like?

My current understanding is that the answer will look something like this:

(deftask dev-repl
  (set-env! …)
  (repl))

Answer 1

at the command line

You can achieve this to some degree at the command line, without creating a build.boot file:

In C:\\dev\\my_project :

boot -r src repl -n my-project.utils

• boot -r src : starts boot with src on the "resource paths", which is the set of directories that will be accessible within the JVM.
• repl -n my-project.utils starts a REPL, requires your namespace, and enters it.

While the REPL is running, and after you have edited C:\\dev\\my_project\\src\\my_project\\utils.clj , you can reload it at the REPL like this:

my-project.utils=> (require 'my-project.utils :reload)
nil

minimal build.boot

Alternatively, you could create the file C:\\dev\\my_project\\build.boot with these contents:

(set-env! :resource-paths #{"src"})

(deftask dev 
  "Run a development REPL"
  []
  (repl :init-ns 'my-project.utils))

Then, in C:\\dev\\my_project :

boot dev

Which will also start a REPL in your namespace, but requires less command-line configuration as we've performed the configuration in build.boot , which boot will automatically evaluate.

Note: from a Clojure REPL, regardless of build tool, you can require any namespace (as long as it's on the JVM's class path) with the require function and enter it with the in-ns function.

build.boot with automatic reloading

Finally, it's possible to combine features of Boot to achieve a development workflow oriented around automatically reloading code.

In C:\\dev\\my_project\\build.boot :

(set-env! :resource-paths #{"src"})

(require '[boot.core :as core]
         '[boot.pod  :as pod])

(deftask load-ns
  "Loads the my-project.utils namespace in a fresh pod."
  []
  (let [pods (pod/pod-pool (core/get-env))]
    (core/with-pre-wrap [fileset]
      (pod/with-eval-in (pods :refresh)
        ;; We require indirectly here so that errors from my-project.utils have
        ;; proper line and column information.
        (require 'my-project.load-impl))
      fileset)))

(deftask dev
  "Watches source code and loads my-project/utils every time code changes."
  []
  (comp (watch)
        (load-ns)))

In C:\\dev\\my_project\\src\\my_project\\load_impl.clj :

(ns my-project.load-impl)

(require 'my-project.utils)

In C:\\dev\\my_project\\src\\my_project\\utils.clj :

(ns my-project.utils
  (:require
    [clojure.string :as s]))

(defn my-range [start end]
  (take (- end start) (iterate inc start)))

(println "In the code!")
(println "(my-range 0 10) = " (my-range 10 20))

Back at the command prompt, type boot dev . You should see some println output, and every time you edit and save the file you should see it again, reflecting any changes you made.