- ref object field #!optional defaultprocedure
- ~ object field #!optional defaultprocedure
Access value in object specified by field. If there is no such value, signal an error.
~ is the same procedure as ref.
If object is a sparse type, meaning its fields can be "empty" or "unassigned" (such as a hashtable) and the requested field is empty, the value of default is returned, if that argument is supplied, or an error is signaled.
Note that this is an SRFI-17 getter-with-setter, so the value specified by field can be set with:
(set! (ref object field) value)