WRITING ANNOTATIONS FOR LOGIC JAVA HOW TO

The environment is basically a huge HashMap that contains all the identifiers and the values assigned to them. The evaluator also consists of two parts: the environment, and the evaluator itself. Kind of pointless, I know, but it felt more ‘pure’, and it actually came in handy later. However, to stay closer to Norvig’s implementation, I actually flatten the data structure during tokenization and re-parse it into a tree structure later. The abstract syntax tree (AST) is already defined by the annotation-level: etc. In AnnotationScript, that’s easy: every annotation contains a single token. Tokenization means reading the input and dividing it into useful parts, such as +, if and str/starts-with?. The parser consists of two steps: tokenization, and constructing the abstract syntax tree. There are two parts to the AnnotationScript interpreter: the parser and the evaluator. (In fact, it’s a great stepping stone for implementing your own LISP and gain that nerd cred rite of passage for yourself as well.

WRITING ANNOTATIONS FOR LOGIC JAVA HOW TO

I googled around a bit and found a blog post by Peter Norvig where he explained, step by step, how to implement LISP in Python. Also, 11 is the ‘crazy number’ (het gekkengetal) in Dutch tradition, which seemed appropriate. You don’t want to rack up that cyclomatic complexity, after all. I decided to end at because twelve levels of nesting felt like enough to me. I decided to start with because as Dijkstra so eloquently explained, all numbering should start at zero. The only drawback is that I had to define an annotation for each level of nesting, which means that there would be a limit to how deeply a program could be nested. So without further ado, here are Hello World and FizzBuzz: package nl. import nl. import nl. ( 'println' ) ( ''Hello world!'' ) public class HelloWorld Now, almost ten years later, I’m finally ready to announce AnnotationScript! My answer has always been “no” – until now. So, ever since I decided to grow one myself in 2011, naturally, people asked me if I was going to create one, too. In 2008, a story went viral that the creators of successful programming languages all have beards ( here’s a summary about that from 2012).

The ridiculous properties of MetaScript.

The limiting restrictions of anotations.This story is going to be a rollercoaster, so I’ve decided to split it up so you can catch your breath between loopings. It’s available on GitHub.įor the why and the how, read on! Table of contents I have created a programming language whose syntax is expressed entirely in Java annotations. AnnotationScript: abusing Java annotations to the extreme

Writing annotations for logic java