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Allegro CL

ANSI Common Lisp   5 Data and Control Flow   5.3 Dictionary of Data and Control Flow

 5.3.40 every, some, notevery, notany Function

Syntax:
every predicate &rest sequences+    generalized-boolean

some predicate &rest sequences+    result

notevery predicate &rest sequences+    generalized-boolean

notany predicate &rest sequences+    generalized-boolean

Arguments and Values:
predicate - a designator for a function of as many arguments as there are sequences.

sequence - a sequence.

result - an object.

generalized-boolean - a generalized boolean.

Description:
every, some, notevery, and notany test elements of sequences for satisfaction of a given predicate. The first argument to predicate is an element of the first sequence; each succeeding argument is an element of a succeeding sequence.

Predicate is first applied to the elements with index 0 in each of the sequences, and possibly then to the elements with index 1, and so on, until a termination criterion is met or the end of the shortest of the sequences is reached.

every returns false as soon as any invocation of predicate returns false. If the end of a sequence is reached, every returns true. Thus, every returns true if and only if every invocation of predicate returns true.

some returns the first non-nil value which is returned by an invocation of predicate. If the end of a sequence is reached without any invocation of the predicate returning true, some returns false. Thus, some returns true if and only if some invocation of predicate returns true.

notany returns false as soon as any invocation of predicate returns true. If the end of a sequence is reached, notany returns true. Thus, notany returns true if and only if it is not the case that any invocation of predicate returns true.

notevery returns true as soon as any invocation of predicate returns false. If the end of a sequence is reached, notevery returns false. Thus, notevery returns true if and only if it is not the case that every invocation of predicate returns true.

Examples:
``` (every #'characterp "abc")  true
(some #'= '(1 2 3 4 5) '(5 4 3 2 1))  true
(notevery #'< '(1 2 3 4) '(5 6 7 8) '(9 10 11 12))  false
(notany #'> '(1 2 3 4) '(5 6 7 8) '(9 10 11 12))  true
```

Exceptional Situations:
Should signal type-error if its first argument is neither a symbol nor a function or if any subsequent argument is not a proper sequence.

Other exceptional situations are possible, depending on the nature of the predicate.

See Also:
and, or, Section 3.6 Traversal Rules and Side Effects

Notes:
``` (notany predicate {sequence}*) ==(not (some predicate {sequence}*))
(notevery predicate {sequence}*) ==(not (every predicate {sequence}*))
```

Allegro CL Implementation Details:
None.

© Franz Inc. 1998-2017 - File last updated 01-11-2017