Getting started
Table of contents
Trying J* from the Browser
An online version of the interpreter is provided here if you want to hop straight in without dealing with the installation process. While this is a pretty convinient way to get a feel for the language, installing it on your machine is still reccomended if you want to follow along with the language guide, as the online interpeter has some limitations.
Installation
Precompiled binaries
If you are on Windows or Linux, then you are in luck! Precompiled binaries are provided here for such platforms and the installation is as simple as unpacking the archive in case you chose to download the zip or tar.gz files, or double clicking on the installer program for the -installer packages.
In case you’ve downloaded the zip or tar.gz archive, moving its contents in a standard location on your system is reccomended in order to have easy access to the jstar and jstarc command line applications through the terminal.
For example, on Windows, a good place to put the bin, lib and include folders inside the archive is C:\Program Files\jstar. (Be sure to also add this folder to your PATH environment variable!)
For Linux, the reccomended path is /usr/local.
Installing from source
If you use another operating system, do not fret!
By its design, J* is pretty minimal and has very few dependencies, which makes compiling it from source pretty easy. All you basically need is cmake and a c/c++ compiler. You can get more info by reading the compilation section of the README file.
The command line interface
If you decided to install J* on you local machine, then the cli application will be your primary way of interacting with the language while learning it, so spending a few words on it will be beneficial.
J* is an embeddable language first and foremost, but nonetheless an executable called jstar (jstar.exe on Windows) is provided to start using the language without first embedding it into another program.
Using the jstar command line interface is pretty easy if you followed the installation process above; simply fire up a terminal and issue the jstar command. You will be greeted by a prompt and a blinking cursor. This means that you entered the repl, or read-eval-print loop. This is the state that the jstar application will enter when you invoke it witout arguments. In this state you can simply write lines of J* code and the interpreter will execute them, printing any result that the code produces.
You can even use the repl as a simple calculator! In fact, the interpreter will assign the result of the last expression to the _ (underscore) variable, so that you can chain calculations:
J*>> 20 + 5
25
J*>> _ / 5
5
But what if you want to execute code written on some file? That’s pretty easy aswell. Simply open your favourite text editor, type in some J* code, save it on file and then exectue the jstar program passing the path to the file as an argument: jstar path/to/file.jsr. (jsr is the typical extension that we give to J* source files, but its not required)
The jstar executable can also take in additional options that modify its behaviour, to see them alongside a description simply pass the -h option to it.
Now you know all you need to start using J* on your machine.