4.10 Mutable Pairs and Lists
A mutable pair is like a pair created by cons, but
it supports set-mcar! and set-mcdr! mutation
operations to change the parts of the mutable pair (like traditional Lisp and
A mutable list is analogous to a list created with pairs, but
instead created with mutable pairs.
A mutable pair is not a pair; they are completely
separate datatypes. Similarly, a mutable list is not a
list, except that the empty list is also the empty mutable
list. Instead of programming with mutable pairs and mutable lists,
data structures such as pairs, lists, and hash tables are practically
always better choices.
A mutable list can be used as a single-valued sequence (see
Sequences). The elements of the mutable list serve as elements
of the sequence. See also in-mlist.
4.10.1 Mutable Pair Constructors and Selectors
Returns a newly allocated
element is a
and second element is d