sclass LASScope {
  // variables declared in this scope, with type/value description
  gettable new Map<S, LASValueDescriptor> declaredVars;
  
  // optional parent scope
  // (we can see the parent's variables in this scope too, unless they
  // are redeclared)
  settable LASScope parentScope;
  
  // true = we may outlive the parent scope
  // (e.g. when we're a lambda)
  settable bool parentIsDetached;
}