Satisfying a One-Argument Test

ToC

Allegro CL

ANSI Common Lisp

17 Sequences

17.2 Rules about Test Functions

17.2.2 Satisfying a One-Argument Test

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.

Operators that have One-Argument Tests to be Satisfied
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

The element E_i 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 E_i as an argument, and yielding an object Z_i to be used for comparison. (If there is no :key argument, Z_i is E_i.)

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, Z_i. An E_i 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, Z_i. An E_i 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