Cmel

Cmel (see-mel) is short for Caramel, the name of my cat. It's my implementation of Lox from Crafting Interpreters by Robert Nystrom.

Features

Here are the features which separate Cmel from Lox.

• Support for 2^24 constant values in a script
• Local const values
• Has a break statement to exit from loops early
• Built-ins
  • input() to get a string from stdin
  • readFile() to read a file from the file system
• Primitive methods (e.g. "string".length())

Usage

Compile the project using

./build.sh

Then, you can either run cmel as a REPL

./cmel

or execute a file by passing it the path

./cmel <filepath>

Testing

To test the code, first build the executable using the build script, then navigate to the test folder and run

node --test

Todo

Language Features

• Widen const to work for global variables
• Arrays/Lists
• File Reading
• Postfix Operators (e.g. ++ and --)
• Ternary Operator
• Modulo Operator
• String Escape Characters
• String interpolation
• Implicit convert to string on all types for concatenation
• Try/Catch
• Anonymous Functions
• Modules
• User facing Hash Tables (Including non-string keys)
• Continue Statement
• Break Statement
• Switch Statement
• Typeof operator
• toString method on instances

Tooling

• Syntax Highlighter
• Language Server
• Test Runner

Misc

• In chapter 18 it's mentioned that a <= b should not be the same as !(a > b) but in cmel it is. Fix by introducing dedicated instructions for <=, >= and maybe != while you're at it