“clj” is a command-line tool in the Clojure programming language ecosystem. It is used to start a REPL (Read-Eval-Print Loop) or invoke a specific function with data in a Clojure environment. The tool provides flexibility and convenience for working with Clojure code and interacting with a Clojure runtime.
The primary purpose of the “clj” tool is to facilitate the development and exploration of Clojure programs. It allows developers to quickly start a REPL session, which is an interactive environment where they can enter Clojure expressions, have them evaluated, and see the results immediately. The REPL is a powerful tool for experimentation, debugging, and iterative development in Clojure.
In addition to starting a REPL, the “clj” tool also allows developers to invoke a specific function with data without entering the REPL interactively. This feature is useful for running Clojure scripts or executing specific parts of a program without the need to manually enter code in the REPL.
To provide flexibility and configurability, the “clj” tool allows for defining options and dependencies in a “deps.edn” file. “deps.edn” is a configuration file used in Clojure projects to manage dependencies, specify build settings, and define various project options. By configuring the “deps.edn” file, developers can control aspects of the “clj” tool, such as specifying required libraries, customizing the environment, or setting up aliases for common tasks.
The “clj” tool is part of the Clojure command-line tools (CLI) ecosystem, which provides a set of command-line utilities for working with Clojure projects. These tools, including “clj,” aim to streamline the development workflow by providing a consistent and efficient way to manage dependencies, build projects, and interact with Clojure code from the command line.
Using “clj” and the Clojure CLI tools, developers can quickly start a REPL session to experiment with code, evaluate expressions, and interact with the Clojure runtime. It provides a convenient way to explore the language, test code snippets, and debug issues. Additionally, by leveraging the configuration options in the “deps.edn” file, developers can customize and extend the behavior of the “clj” tool to suit their specific needs.
clj Command Examples
1. Start a REPL (interactive shell):
# clj
2. Execute a function:
# clj -X namespace/function_name
3. Run the main function of a specified namespace:
# clj -M -m namespace args
4. Prepare a project by resolving dependencies, downloading libraries, and making / caching classpaths:
# clj -P
5. Start an nREPL server with the CIDER middleware:
# clj -Sdeps ':deps nrepl :mvn/version "0.7.0" cider/cider-nrepl :mvn/version "0.25.2"' -m nrepl.cmdline --middleware '["cider.nrepl/cider-middleware"]' --interactive
6. Start a REPL for ClojureScript and open a web browser:
# clj -Sdeps ':deps org.clojure/clojurescript :mvn/version "1.10.758"' --main cljs.main --repl
Summary
In summary, “clj” is a command-line tool in the Clojure ecosystem used to start a REPL or invoke a specific function with data. It provides a convenient way to interact with Clojure code, experiment with expressions, and test functionality. The tool can be configured using the “deps.edn” file to define options, manage dependencies, and customize the Clojure development environment. With the “clj” tool and the broader Clojure CLI tools, developers have a powerful command-line interface for working with Clojure projects.