The compiler only knows how to emit functions and how to link function names. I did that so I had fewer things hardcoded into the compiler and allows me to write the language in the language.
To do that, I had to add either a %wasm { ... } code block, and a %stack { ... } type.
%wasm { ... }: can only be used as a function body, not as an expression. It is literally the code that will be emited to WAST. The parameter names remain the same (prefixed with $ as WAST indicates). Other symbols can be resolved with fully::qualified::names.
%stack { wasm="i32", size=4 }: it is a type literal, it indicates how much memory should be allocated in structs (size) and what type to use in locals and function parameters (wasm, it needs a better name).
/** We first define the type `int` */
type int = %stack { wasm="i32", size=4 }
/** Implement some operators for the type `int` */
impl int {
fun +(lhs: int, rhs: int): int = %wasm {
(i32.add (get_local $lhs) (get_local $rhs))
}
fun -(lhs: int, rhs: int): int = %wasm {
(i32.sub (get_local $lhs) (get_local $rhs))
}
fun >(lhs: int, rhs: int): boolean = %wasm {
(i32.gt_s (get_local $lhs) (get_local $rhs))
}
}
fun fibo(n: int, x1: int, x2: int): int = {
if (n > 0) {
fibo(n - 1, x2, x1 + x2)
} else {
x1
}
}
#[export "fibonacci"] // "fibonacci" is the name of the exported function
fun fib(n: int): int = fibo(n, 0, 1)
Last modified 21 November 2020