vurv78 / expressionscript

Expression2 rewritten in Haxe

ExpressionScript

Expression2 rewritten in Haxe.

⚠️ Notice ⚠️

This was a cool project, but I might've put too much of an emphasis on backwards compatibility, the one thing holding me back on E2 in the first place. Since I'm not making progress on this nor E2, you might want to see https://github.com/Vurv78/Expressive while this is on hold. It doesn't help that I've kind of fallen out of heart for Haxe. If this does come back, it may be in Rust ⚙️.

Readme

This was originally created to be a template to rewrite E2 for S&box, however at this point S&Box looks awful and I'm not interested in C#.
All credit and ownership of Expression2 goes to the wireteam & wiremod.

Transpiler

This project allows you to convert ExpressionScript code to any language, as long as a transpiler is provided.
By default a Lua transpiler is provided and more may come.

Differences

No normal

Normal is a type that came before number, however nobody uses it and it just complicates things.

No inputs

For obvious reasons, there's no io or entities in this as this is meant to be run in the browser, or simply on your pc.

Optimized

The language is optimized for speed. E2 was known to be very slow, and this is no longer the case through typing and other optimizations.
*Although, admittedly Haxe is nowhere near the best language for trying to get something to be fast.

General State

Here's a general status of each part of the language.

Name	Status	Desc
Preprocessor	🚧	No support for directives (I mean what would they do?). Of course they alongside comments are stripped out of code. Missing #ifdef, etc.
Tokenizer	✔️	Tokenizer should be completely finished. Some operators and grammar might be missing that I'm unaware of.
Parser	🚧🏗️	It is nearly done, however some things like #include are missing, and some statements/expressions might be buggy.
Optimizer	❌	Hasn't been started and there are no plans for this yet.
Compiler	🚧	I have not started work on this yet.
(Lua) Transpiler	✔️🏗️	Mostly done.
Tests	✔️	Unit tests are used to verify integrity of the language.

Running Tests

Tests are using the utest library.
Use haxe test.hxml to run them.

expressionscript's Issues

update readme

Expression4 link -> Expressive

Browser demo/repl

Since this is in Haxe, I could just compile this to javascript and deploy to github pages at https://vurv78.github.io/ExpressionScript.

Then everyone could try it out. Would just be the transpiler for now.. for obvious reasons

Handle constants through the preprocessor

E2 handles constants through the tokenizer which is just really weird and unintuitive. (We mirrored that for now and it works fine but it feels gross)

Use Monaco for Playground

Would be much nicer

Fix indexing operator

For some reason even though we accept a comma token it won't move past there. It will instead stay at the comma and not be able to accept a type token.

Repro

E[1,number]

Add #include statement

Add another statement in the parser that accepts #include "path". (Might also need to add a new keyword to tokenizer)
See https://github.com/wiremod/wire/wiki/Expression-2#include-directive for more info on what include is.

( It is basically just #include from languages like C++, except it is not through the preprocessor but it is turned into a function that runs in another scope.. yeah it's weird.. )

If you really want to go above and beyond you can also implement it in the lua transpiler side as just require(string).

Preprocessor not taking account for strings

"#"

Will break because the preprocessor just scans for hashtags without considering if they are inside a string.

Do while statement

Recently merged into the E2 compiler.

Fix unit tests

Giving cryptic errors that I don't want to bother looking into right now.

Use hashlink

Hashlink is miles ahead of c++ for Haxe. Looks like it takes 1/10th of the time to compile, all into one neat file.

Try catch statement for parser/transpiler

Finished up the work on the wiremod repo, this will have to wait until the Compiler is in a working state

Null Safe

We should be able to enable --macro nullSafety("base", Strict)
Without any errors

No Dynamic

We don't want dynamic typing anywhere (It slows down statically typed targets (C++, Hashlink) by a LOT)

Here's where it's used

• [Compiler] Temporary value for E2Context is of type Dynamic
• [Lua Transpiler] call instruction
• [Lua Transpiler] callInstruction
• [Parser] Arguments passed to callInstruction are Dynamic, as we use reflection