fddl Programming Language

fddl is a small programming language inspired by various languages, designed to help learn language implementation concepts in Rust.

I have, off and on throughout the last 15 or so years attempted to learn a programming language of some sort. I could always get through the basics, but would get stuck with any real world projects. And I wouldn't know who to turn to even if I knew where to start.

So I started learning Rust and really like it. So I've been following some tutorials and the Crafting Interpretors site as guides for this very problematic programming language.

I like aspects of so many programming languages, but I don't really like any of them, so I always found it hard to pick one and stick with it. But I had the same problem playing World of Warcraft, too.

So I, like many of you, decided to make a hobby programming language to see what may be able to be done with it.

Features

• Custom syntax with unique operators and keywords
• Documentation comments using #, similar to Rust's style
• Lexer and parser built from scratch in Rust

Getting Started

To run the REPL:

cargo run

To run a fddl script:

cargo run path/to/script.fddl

Examples

##! This is a sample module

module math {

    ### Computes the square of a number
    func square(x) => x ^ 2;
}

define $number := 5;
print(`The square of $number is ${math.square($number)}`);

(At least for right now.)

License

This project is licensed under the MIT License.

---

Notes and Next Steps

• Added first new set of tokens and features, added the first lexer tests.
• parser module is a placeholder.
• interpreter module is a placeholder.
• Implement a more robust error handling mechanism instead of using stderr.
• Imlement string interpolation (backticks with $variable)
• Continue to expand tests to cover all new syntax and features.

---

Running the Project

Make sure your project compiles and the tests pass:

cargo build
cargo test