KDLScript 🫂💗📜

KDLScript, the KDL-based programming language!

KDLScript ("Cuddle Script") is a "fake" scripting language that actually just exists to declare type/function signatures without tying ourselves to any particular language's semantics. It exists to be used by ABI Cafe.

Basically, KDLScript is a header format we can make as weird as we want for our own usecase:

struct "Point" {
    x "f32"
    y "f32"
}

enum "ScaleMode" {
    Width
    Height
}

fn "print" {
    inputs { _ "Point"; }
}

fn "scale" {
    inputs { _ "Point"; factor "f32"; scalemode "ScaleMode"; }
    outputs { _ "Point"; }
}

fn "sum" {
    inputs { _ "&[Point; 4]"; }
    outputs { _ "Point"; }
}

Ultimately the syntax and concepts are heavily borrowed from Rust, for a few reasons:

• The author is very comfortable with Rust
• This (and ABI Cafe) were originally created to find bugs in rustc
• Rust is genuinely just a solid language for interfaces! (Better than C/C++)

The ultimate goal of this is to test that languages can properly communicate over FFI by declaring the types/interface once and generating the Rust/C/C++/... versions of the program (both caller and callee) and then linking them into various combinations like "Rust calls C++" to check that the values are passed correctly.

Quickstart

kdl-script is both a library and a CLI application. The CLI is just for funsies.

The main entry point to the library is Compiler::compile_path or Compiler::compile_string, which will produce a TypedProgram. See the types module docs for how to use that.

The CLI application can be invoked as kdl-script path/to/program.kdl to run a KDLScript program.