title: lisp filter out results from list not matching predicate
body: <p>I am trying to learn lisp, using emacs dialect and I have a question.
  let us say list has some members, for which predicate evaluates to false.  how do I create a new list without those members?  something like <code>{ A in L: p(A) is true }</code>. in python there is filter function, is there something equivalent in lisp?  if not, how do I do it?</p>
  
  <p>Thanks</p>