Using Go packages

Until Xo has its own ecosystem, any Go package is one line away:

gointerop/main.xo

use go "strings"
use go "net/url"

fn main(os: Os) ! {
  os.stdio.println(strings.to_upper("hello from go"))
  let u = url.parse("https://xolang.dev/docs?tab=tour")?
  os.stdio.println("${u.hostname()} ${u.query().get("tab")}")
}

Output:

HELLO FROM GO
xolang.dev tour

xo check, build, run, and test generate the bindings themselves.
Names follow Xo’s style: ToUpper is to_upper.
Go’s (T, error) becomes T ! go.Error, so url.parse(...)? works like any Xo call, and a pointer that may be nil becomes T?.
Every call into Go performs the go effect. Go code can reach files and the network without a capability, so a pub function that calls Go must say uses go, and that escape stays visible in signatures.

Native builds can call C the same way with use c "header.h"; see section 4.5 of the specification.

That is the tour. The specification covers everything in full, and the diagnostics reference explains every error code.

Docs

Tour

Reference

Using Go packages