typechecker: Type check generic functions independently of their use
It looks to me like we aren't checking generic functions "on their own". Instead, we only check them with type variables filled in at their call sites. This leads to quite strange error reporting and in some cases even C++ that doesn't compile.
Currently, writing this is not an error:
fn to_minus_42<T>(anon a: T) -> T {
return -42
}
fn main() {
to_minus_42(-12)
}However, this is:
fn to_minus_42<T>(anon a: T) -> T {
return -42
}
fn main() {
to_minus_42(12 as! u32)
}Also notice where it is reported:
Error: Type mismatch: expected ‘u32’, but got ‘i64’
───┬─ src/main.jakt:2:5
1 │ fn to_minus_42<T>(anon a: T) -> T {
2 │ return -42
│ ─────────┬
│ ╰─ Type mismatch: expected ‘u32’, but got ‘i64’
3 │ }
───┴─Lastly, consider this case, which will type check but doesn't compile:
fn unwrap<T>(anon a: Optional<T>) -> T {
return None
}
fn main() {
unwrap(Some(42))
}
SerenityOS / jakt
The Jakt Programming Language
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