Building a CLI Tool

This tutorial will guide you through creating a simple command-line interface tool in Axon that echoes back arguments with a prefix.

Prerequisites

• Axon compiler installed (v0.1.0 or higher)
• Basic understanding of S-expressions

Step 1: Initializing the Project

Create a new directory and initialize an Axon project using axon-pkg:

mkdir echo-cli
cd echo-cli
axon init

This will generate a project.axs manifest file and a src/main.axs file.

Step 2: Parsing Arguments

In Axon, command line arguments are accessed via the std/os standard library module. Open src/main.axs and replace its contents with:

(import std/os)
(import std/io)

(fn main ()
  (let args (os.args))

  (if (<= (len args) 1)
    (do
      (io.println "Usage: echo-cli <message>")
      (os.exit 1))

    ;; Else, echo the arguments
    (let message (join (slice args 1 (len args)) " "))
    (io.println (+ "Echo: " message))))

Step 3: Compiling the Tool

To compile the tool into a standalone native binary, run:

axon build --release

Because Axon compiles directly to machine code via LLVM, this will produce a highly optimized binary in the build/ directory without any dependencies on an interpreter or virtual machine.

Step 4: Running

Test your new CLI tool:

./build/echo-cli "Hello Axon World!"

Output:

Echo: Hello Axon World!

Congratulations! You’ve just built your first high-performance native CLI tool using Axon.