Version: 5.1.2

### 2Growable Vectors

 (require data/gvector)

A growable vector (gvector) is a mutable sequence whose length can change over time. A gvector also acts as a dictionary (dict? from racket/dict), where the keys are zero-based indexes and the values are the elements of the gvector. A gvector can be extended by adding an element to the end, and it can be shrunk by removing any element, although removal can take time linear in the number of elements in the gvector.

Two gvectors are equal? if they contain the same number of elements and if the contain equal elements at each index.

 (make-gvector [#:capacity capacity]) → gvector? capacity : exact-positive-integer? = 10
Creates a new empty gvector with an initial capacity of capacity.

 (gvector elem ...) → gvector? elem : any/c
Creates a new gvector containing each elem in order.

 (gvector? x) → boolean? x : any/c
Returns #t if x is a gvector, #f otherwise.

 (gvector-ref gv index [default]) → any/c gv : gvector? index : exact-nonnegative-integer? default : any/c = (error ....)
Returns the element at index index, if index is less than (gvector-count gv). Otherwise, default is invoked if it is a procedure, returned otherwise.

 (gvector-add! gv value ...) → void? gv : gvector? value : any/c
Adds each value to the end of the gvector gv.

(gvector-set! gv index value)  void?
gv : gvector?
index :
 (and/c exact-nonnegative-integer? (
value : any/c
Sets the value at index index to be value. If index is (gvector-count gv)that is, one more than the greatest used index—the effect is the same as (gvector-add! gv value).

(gvector-remove! gv index)  void?
gv : gvector?
index :
 (and/c exact-nonnegative-integer? (
Removes the item at index, shifting items at higher indexes down. Takes time proportional to (- (gvector-count gv) index).

 (gvector-count gv) → exact-nonnegative-integer? gv : gvector?
Returns the number of items in gv.

 (gvector->vector gv) → vector? gv : gvector?
Returns a vector of length (gvector-count gv) containing the elements of gv in order.

 (in-gvector gv) → sequence? gv : gvector?
Returns a sequence whose elements are the elements of gv. Mutation of gv while the sequence is running changes the elements produced by the sequence. To obtain a sequence from a snapshot of gv, use (in-vector (gvector->vector gv)) instead.

 (for/gvector (for-clause ...) body ...+)
 (for*/gvector (for-clause ...) body ...+)
Analogous to for/list and for*/list, but constructs a gvector instead of a list.

Unlike for/list, the body may return zero or multiple values; all returned values are added to the gvector, in order, on each iteration.