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  ANSI Common Lisp   17 Sequences   17.3 Dictionary of Sequences

17.3.20 concatenate Function

Syntax:
concatenate result-type &rest sequences    result-sequence

Arguments and Values:
result-type - a sequence type specifier.

sequences - a sequence.

result-sequence - a proper sequence of type result-type.

Description:
concatenate returns a sequence that contains all the individual elements of all the sequences in the order that they are supplied. The sequence is of type result-type, which must be a subtype of type sequence.

All of the sequences are copied from; the result does not share any structure with any of the sequences. Therefore, if only one sequence is provided and it is of type result-type, concatenate is required to copy sequence rather than simply returning it.

It is an error if any element of the sequences cannot be an element of the sequence result.

If the result-type is a subtype of list, the result will be a list.

If the result-type is a subtype of vector, then if the implementation can determine the element type specified for the result-type, the element type of the resulting array is the result of upgrading that element type; or, if the implementation can determine that the element type is unspecified (or *), the element type of the resulting array is t; otherwise, an error is signaled.

Examples:
(concatenate 'string "all" " " "together" " " "now")  "all together now"
(concatenate 'list "ABC" '(d e f) #(1 2 3) #*1011)
 (#\A #\B #\C D E F 1 2 3 1 0 1 1)
(concatenate 'list)   NIL

  (concatenate '(vector * 2) "a" "bc") should signal an error

Exceptional Situations:
An error is signaled if the result-type is neither a recognizable subtype of list, nor a recognizable subtype of vector.

An error of type type-error should be signaled if result-type specifies the number of elements and the sum of sequences is different from that number.

See Also:
append

Allegro CL Implementation Details:
None.

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