(r5rs.info.gz) Vectors

Info Catalog

(r5rs.info.gz) Strings

(r5rs.info.gz) Other data types

 
 6.3.6 Vectors
 -------------
 
 Vectors are heterogenous structures whose elements are indexed by
 integers.  A vector typically occupies less space than a list of the
 same length, and the average time required to access a randomly chosen
 element is typically less for the vector than for the list.
 
 The _length_ of a vector is the number of elements that it contains.
 This number is a non-negative integer that is fixed when the vector is
 created.  The _valid indexes_ of a vector are the exact non-negative
 integers less than the length of the vector.  The first element in a
 vector is indexed by zero, and the last element is indexed by one less
 than the length of the vector.
 
 Vectors are written using the notation #(OBJ ...,).  For example, a
 vector of length 3 containing the number zero in element 0, the list
 `(2 2 2 2)' in element 1, and the string `"Anna"' in element 2 can be
 written as following:
 
 
      #(0 (2 2 2 2) "Anna")
 
 Note that this is the external representation of a vector, not an
 expression evaluating to a vector.  Like list constants, vector
 constants must be quoted:
 
 
      '#(0 (2 2 2 2) "Anna")
                ==>  #(0 (2 2 2 2) "Anna")
 
  -- procedure: vector? obj
      Returns #t if OBJ is a vector, otherwise returns #f.
 
  -- procedure: make-vector k
  -- procedure: make-vector k fill
      Returns a newly allocated vector of K elements.  If a second
      argument is given, then each element is initialized to FILL.
      Otherwise the initial contents of each element is unspecified.
 
 
  -- library procedure: vector obj ...,
      Returns a newly allocated vector whose elements contain the given
      arguments.  Analogous to `list'.
 
      (vector 'a 'b 'c)                      ==>  #(a b c)
 
 
  -- procedure: vector-length vector
      Returns the number of elements in VECTOR as an exact integer.
 
  -- procedure: vector-ref vector k
      K must be a valid index of VECTOR.  `Vector-ref' returns the
      contents of element K of VECTOR.
 
      (vector-ref '#(1 1 2 3 5 8 13 21)
                  5)
                ==>  8
      (vector-ref '#(1 1 2 3 5 8 13 21)
                  (let ((i (round (* 2 (acos -1)))))
                    (if (inexact? i)
                        (inexact->exact i)
                        i)))
                ==> 13
 
 
  -- procedure: vector-set! vector k obj
      K must be a valid index of VECTOR.  `Vector-set!' stores OBJ in
      element K of VECTOR.  The value returned by `vector-set!' is
      unspecified.
 
      (let ((vec (vector 0 '(2 2 2 2) "Anna")))
        (vector-set! vec 1 '("Sue" "Sue"))
        vec)
                ==>  #(0 ("Sue" "Sue") "Anna")
 
      (vector-set! '#(0 1 2) 1 "doe")
                ==>  _error_  ; constant vector
 
 
  -- library procedure: vector->list vector
  -- library procedure: list->vector list
      `Vector->list' returns a newly allocated list of the objects
      contained in the elements of VECTOR.  `List->vector' returns a
      newly created vector initialized to the elements of the list LIST.
 
      (vector->list '#(dah dah didah))
                ==>  (dah dah didah)
      (list->vector '(dididit dah))
                ==>  #(dididit dah)
 
 
  -- library procedure: vector-fill! vector fill
      Stores FILL in every element of VECTOR.  The value returned by
      `vector-fill!' is unspecified.
 
 

Info Catalog

(r5rs.info.gz) Strings

(r5rs.info.gz) Other data types