What's New in v1.15

"The Payloads Release" - two correctness fixes that remove long-standing sharp edges: any scalar can now ride inside an Option or Result, and your function names no longer collide with the C standard library.

It's all backward compatible - no source changes are required to upgrade.

Highlights

• float? / bool? and Result<float, _> / Result<bool, _> now compile - previously only int and string payloads worked.
• Function names can shadow libc symbols - connect, read, write, socket, and friends are now free to use.

Float and Bool Optionals and Results

Before v1.15, only int and string payloads worked inside an Option or Result - a -> float? function wouldn't compile. Now every scalar works, in every position:

fn half(x: float) -> float? {
    if x < 0.0 { return None }
    return Some(x / 2.0)
}

fn divide(a: float, b: float) -> Result<float, string> {
    if b == 0.0 { return Err("division by zero") }
    return Ok(a / b)
}

You can match on them in both statement and expression position:

match half(9.0) {
    Some(v) => print("half is ${v}"),   // half is 4.5
    None => print("negative input"),
}

var result = divide(10.0, 4.0)
var msg = match result {
    Ok(v) => "quotient ${v}",
    Err(e) => "error: ${e}",
}
print(msg)                               // quotient 2.5

The method API works too - .is_some(), .unwrap(), and .unwrap_or(default):

var maybe = half(8.0)
if maybe.is_some() {
    print("got ${maybe.unwrap()}")       // got 4.0
}
print(half(-1.0).unwrap_or(0.0))         // 0.0

Booleans behave the same way:

fn parse_flag(s: string) -> bool? {
    if s == "on" { return Some(true) }
    if s == "off" { return Some(false) }
    return None
}

match parse_flag("on") {
    Some(v) => print("flag is ${v}"),     // flag is true
    None => print("unknown flag"),
}

Function Names Can Shadow libc Symbols

A function named connect, read, write, open, close, socket, send, listen, index, and many others used to fail to compile with a cryptic C error (static declaration of 'connect' follows non-static declaration). Those names are now free to use - the generated C is transparently namespaced, so your Wyn code is completely unaffected:

fn connect(host: string) -> string {
    return "connected to ${host}"
}

fn read(n: int) -> int {
    return n + 1
}

fn main() {
    print(connect("localhost"))          // connected to localhost
    print(read(41))                      // 42
}

Pick the name that reads best for your domain - the compiler handles the rest.

Upgrading

wyn --version        # 1.15.0

No source changes are required - v1.15.0 is a drop-in upgrade over v1.14.0.

See also

• What's New in v1.14 - the Polish Release
• What's New in v1.13 - the Pythonic Release
• Error Handling - Result and Option in depth
• Version History