wren/doc/site/getting-started.markdown

^title Getting Started

Getting Wren up and running on your machine should be pretty straightforward. Tiny C programs with few dependencies are nice that way. "Wren" encompasses two separate artifacts:

• The virtual machine. This is the core chunk of C that executes Wren source code. It is just a library, not a standalone application. It's designed to be embedded in a larger host application. It has no dependencies beyond the C standard library. You can is use as a static library, shared library, or simply compile the source into your app.

• The command line executable. Wren also ships with a CLI wrapper around the VM. This gives you a way to run Wren code from the command-line, and also includes modules for talking to the operating system. It depends on libuv for that.

If you're on a Unix or Mac and you can rock a command line, it's just:

:::bash
$ git clone https://github.com/munificent/wren.git
$ cd wren
$ make
$ ./wren

This builds both the VM and the CLI. It downloads libuv automatically for you. The release build of the CLI goes right into the repo's top level directory. Binaries for other configurations are built to bin/. Static and shared libraries for embedding Wren get built in lib/.

For Mac users, there is also an XCode project under project/xcode. For Windows brethren, project/msvc2013 contains a Visual Studio solution. Note that these may not have the exact same build settings as the makefile. The makefile is the "official" way to compile Wren.

If you only want to build the VM, you can do:

:::bash
$ make vm

This will compile the VM to static and shared libraries. It will not even download libuv since it isn't needed.

Interactive mode

The above instructions will drop you into Wren's standalone interpreter in interactive mode. You can type in a line of code, and it will immediately execute it. Here's something to try:

:::wren
System.print("Hello, world!")

Or a little more exciting:

:::wren
for (i in 1..10) System.print("Counting up " + i.toString)

You can exit the interpreter using good old Ctrl-C or Ctrl-D, or just throw your computer to the ground and storm off.

Running scripts

The standalone interpreter can also load scripts from files and run them. Just pass the name of the script to wren. Create a file named "my_script.wren" in your favorite text editor and paste this into it:

:::wren
for (yPixel in 0...24) {
  var y = yPixel / 12 - 1
  for (xPixel in 0...80) {
    var x = xPixel / 30 - 2
    var x0 = x
    var y0 = y
    var iter = 0
    while (iter < 11 && x0 * x0 + y0 * y0 <= 4) {
      var x1 = (x0 * x0) - (y0 * y0) + x
      var y1 = 2 * x0 * y0 + y
      x0 = x1
      y0 = y1
      iter = iter + 1
    }
    System.write(" .-:;+=xX$& "[iter])
  }

  System.print("")
}

Now run:

:::bash
$ ./wren my_script.wren

Neat, right? You're a Wren programmer now! The next step is to read more docs and learn your way around the language. If you run into bugs, or have ideas or questions, any of the following work:

• Ask on the Wren mailing list.
• Tell me on twitter at @munificentbob.
• File a ticket at the GitHub repo.
• Send a pull request.
• Email me at robert@stuffwithstuff.com.