loxy-sharp

Learning how to create a programming language by implementing a tree-walk interpreter in C#.

This is my own attempt at building a version of the Lox language created by Robert Nystrom in the book Crafting Interpreters.

Lox Grammar (BNF)

expression -> literal | unary | binary | grouping ;
literal    -> NUMBER | STRING | "true" | "false" | "nil" ;
grouping   -> "(" expression ")" ;
unary      -> ( "-" | "!" ) expression ;
binary     -> expression operator expression ;
operator   -> "==" | "!=" | "<" | "<=" | ">" | ">=" | "+" | "-" | "*" | "/" ;

Terminals which match exact lexemes are quoted strings.

Terminals which are a single lexeme but have text values which may vary are CAPITALISED.

Disclaimer

It's Lox-y because I'm not planning to create an exact replica of Lox. In fact I'm probably going to hack on it and extend it in various ways for the sake of fun and learning. I'm also likely to create a bunch of bugs and inaccuracies.

I don't recommend you use the code in this repository for anything you expect to work! 😃 Take a look at Crafting Interpreters if you are interested in this stuff. An online version of the book is available for free but I highly recommend you buy a physical copy.

Tasks

Things I need to do:

• TODO

Things I want to do:

• Can I implement constant folding as a compile-time optimisation?

• Can I make "everything a class" so that even primitive types can have methods?

• Can I refactor the print statement from being a language feature to be a method in the standard library?

• Extend the standard library with more features such as common string functions.

Ideas

Things I'm thinking about:

• Can I define Lox code in different files and get an interpreter/compiler to load them all to run/build a Lox application? What files extension should I use? *.lxys perhaps?

• Can I add syntax highlighting for Lox code to vscode as a plugin?

• How do I benchmark the speed of the interpreted or compiled language at runtime?

• Can I replace the Program.Report() method with logic to redirect errors and messages to places more interesting than the console. Can I also show the user where in a line the error occurs with surrounding code for context?