• Go

var err error
switch runtime.GOOS {
case "linux":
	err = exec.Command("xdg-open", s).Start()
case "windows":
	err = exec.Command("rundll32", "url.dll,FileProtocolHandler", s).Start()
case "darwin":
	err = exec.Command("open", s).Start()
default:
	err = fmt.Errorf("unsupported platform")
}
b := err == nil

• Go

b := open.Start(s) == nil

• C#

var b = true;
try
{
    Process.Start(new ProcessStartInfo()
    {
        FileName = s,
        UseShellExecute = true,
    });
}
catch { b = false; }

• D

browse(s);

• Pascal

b := OpenUrl(s);

• Perl

my $b = open_browser $s;

• Python

webbrowser.open(s)

• Ruby

cmd = case  RbConfig::CONFIG['host_os']
  when  /mswin|mingw|cygwin/ then "start "
  when  /darwin/ then "open "
  when  /linux|bsd/ then "xdg-open "
  else raise "No OS detected"
end
    
b = system cmd + s

• Rust

webbrowser::open(s).expect("failed to open URL");