make-sequence result-type size &key initial-element → sequence

result-type — a sequence type specifier.

size — a non-negative integer.

initial-element — an object. The default is implementation-dependent.

sequence — a proper sequence.

Returns a sequence of the type result-type and of length size, each of the elements of which has been initialized to initial-element.

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.

 (make-sequence 'list 0) → () 
 (make-sequence 'string 26 :initial-element #\.) 
→ ".........................." 
 (make-sequence '(vector double-float) 2 
                :initial-element 1d0) 
→ #(1.0d0 1.0d0)

(make-sequence '(vector * 2) 3) should signal an error 
(make-sequence '(vector * 4) 3) should signal an error

The implementation.

The consequences are unspecified if initial-element is not an object which can be stored in the resulting sequence.

An error of type type-error must be 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 size is different from that number.

make-array, make-list

(make-sequence 'string 5) ≡ (make-string 5)