Toy Project 2

"DerkWithT" at replit.com / DrkWithT at GitHub

Summary

This will be a toy language interpreter using the tree walk approach on a generated AST. Also, this is a work in progress project for educational fun only. Feel free to fork this.

Features of Rubel

1. Paradigm(s):
   • Imperative
   • Dynamic Scoping
2. Type System:
   • NO "undefined" values for null safety.
   • Variable types are inferred.
   • Mismatched types for an operator causes runtime errors
   • Variables can be mutable or not
   • Booleans are written as $T and $F!
3. Syntax uses similar C-like operators:
   • Example 1: logical operators are &&, ||.
   • Example 2: comparison operators are ==, !=, <, <=, >, >=
   • Example 3: math operators are +, -, *, /, +=, -=
4. Syntax disallows control flow statements outside of function declarations to discourage messy code.

Keywords of Rubel

• module: Declares a module (a separate procedure group) by name.
• use: Includes a module into a script. Specifically, the names of other procedures and constants become visible.
• let: Declares a mutable variable.
• const: Declares a deeply immutable variable. Lists will be immutable for now!
• set: Tells Rubel that we're reassigning a variable. Fails on const valued variables during runtime!
• proc: Declares a procedure.
• if: Executes a block of statements if its conditional is true.
• otherwise: Executes a block of statements if the last if failed.
• while: Executes a block of statements as long as the conditional is true.
• end: Marks the end of a block.
• return: Returns a value from an expression in a procedure.

Examples of Rubel

• See tests to get a sense of Rubel's syntax. I will add more tests later as I continue Rubel.

TODO:

1. Make parser and vartypes.h structures.

• Later add logical expressions.

2. Make interpreter: create scopes as HashTable using bucket list, native function API, and evaluator.
3. Test sample scripts!
4. Refactor and test code even more?

• Add full support for modules: same names across modules should not conflict.
• Implement copy_list_obj to avoid accidental null values when list literals are passed into function arguments... funcargs_destroy calls will free any value through their pointer rather than by value.