concatenate result-type &rest sequences ⇒ result-sequence
| result-type | a sequence type specifier. |
| sequences | a sequence. |
| result-sequence | a proper sequence of type result-type. |
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.
[Reviewer Note by Barmar: Should signal?]
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.
(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
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.