I thought this was working at some point, but it doesn't seem to now. FOO() returns undefined in JS, when it should return 123:
(defun bar (fn) (funcall fn))
(defun foo () (bar (lambda () (return-from foo 123))))
It seems the value stored under the name "ps-return-value" isn't actually returned:
function foo() { try { return bar(function () { throw { 'ps-block-tag' : 'foo', 'ps-return-value' : 123 }; }); } catch (err) { if (err && 'foo' === err['ps-block-tag']) { err['ps-return-value']; } else { throw err; }; }; };