Closures

By default, closures require the same capabilities as the context in which they are created.

function foo()[write_props]: void { // scope has {WriteProperty}
  // inherits [write_props] — the most common usage
  $callable = () ==> {/* ... */};
}

Closures may optionally declare an explicit context list. This is useful when the closure is meant to be passed elsewhere or returned and not directly invoked in the enclosing function.

function bar()[globals]: void { // scope has {AccessGlobals}
  $pure = ()[] ==> {/* ... */}; // create a closure with fewer capabilities
  $defaults = ()[defaults] ==> {/* ... */}; // create a closure with more capabilities
}

Note that in the previous example, $defaults could not be called in bar because bar has only the AccessGlobals capability.