batteries included, some assembly required
In this tutorial/workshop we'll be implementing our own little language, more or less from scratch.
By the end of the tutorial you will be the proud author of a programming language, and will hopefully better understand how programming languages work on a fundamental level.
We will make a relatively simple, but neat language. We aim for the following features:
- A handful of datatypes (integers, booleans and symbols)
- Variables
- First class functions with lexical scoping
- That nice homemade quality feeling
We will not have:
- A proper type system
- Error handling
- Good performance
- And much, much more
The language should be able to interpret the following code by the time we are done:
(define fact
;; Factorial function
(lambda (n)
(if (eq n 0)
1 ; Factorial of 0 is 1
(* n (fact (- n 1))))))
;; When parsing the file, the last statement is returned
(fact 5)The syntax is that of the languages in the Lisp family. If you find the example unfamiliar, you might want to have a look at a more detailed description of the language.
Before we get started, make sure you have installed Java 8 Development Kit (JDK) and Maven (at least version 3).
Clone this repo:
git clone https://github.com/bendiksolheim/diy-lisp-java.gitInstall dependencies:
cd diy-lisp-java
mvn install -DskipTestsAnd you should be pretty much good to go!
Take the time to consider the following points before we get going:
-
Keep things simple
Don't make things more complicated than they need to be. The tests should hopefully guide you every step of the way.
-
Read the test descriptions
Each test has a small text describing what you are going to implement and why. Reading these should make things easier, and you might end up learning more.
-
Use the provided functions
Some of the more boring details are already taken care of. Take the time to look at the functions provided in
Parser.java, and the various imports in files where you need to do some work. -
Description of your language
Unfamiliar with Lisp? Read a description of the language you are going to make in language.md.
The workshop is split up into seven parts. Each consist of an introduction, and a bunch of unit tests which it is your task to make run. When all the tests run, you'll have implemented that part of the language.
Have fun!