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  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 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


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