I'm somewhat new to CL and currently trying to wrap my head around mapcan, #', funcall and closures. Here is a closure, which applies a predicate to a number n and, if correct, returns (list n), el...

Why do we have to use funcall to call higher order functions in Common Lisp? For example, why do we have to use: (defun foo (test-func args) (funcall test-func args)) instead of the simpler: (...