When using one of the functions in the next figure, the elements E of a sequence S are filtered not on the basis of the presence or absence of an object O under a two argument predicate, as with the functions described in Section 17.2.1 (Satisfying a Two-Argument Test), but rather on the basis of a one argument predicate.
assoc-if member-if rassoc-if assoc-if-not member-if-not rassoc-if-not count-if nsubst-if remove-if count-if-not nsubst-if-not remove-if-not delete-if nsubstitute-if subst-if delete-if-not nsubstitute-if-not subst-if-not find-if position-if substitute-if find-if-not position-if-not substitute-if-not
Figure 17-3. Operators that have One-Argument Tests to be Satisfied
The element Ei might not be considered directly. If a :key argument is provided, it is a designator for a function of one argument to be called with each Ei as an argument, and yielding an object Zi to be used for comparison. (If there is no :key argument, Zi is Ei.)
Functions defined in this specification and having a name that ends in ``-if'' accept a first argument that is a designator for a function of one argument, Zi. An Ei is said to satisfy the test if this :test function returns a generalized boolean representing true.
Functions defined in this specification and having a name that ends in ``-if-not'' accept a first argument that is a designator for a function of one argument, Zi. An Ei is said to satisfy the test if this :test function returns a generalized boolean representing false.
17.2.2.1 Examples of Satisfying a One-Argument Test