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Allegro CL |
ANSI Common Lisp 17 Sequences 17.2 Rules about Test Functions
17.2.2 Satisfying a One-Argument TestWhen 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.
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. |