Recovery of reentrant list structures in SLIP
Joseph Weizenbaum · Communications of the ACM · 1969
One consequence of the reference-count-based space-recovery system employed by SLIP is that reentrant list structures are not recovered even when explicitly erased.LISP-like garbage-collection schemes are free of this impediment.They, however, depend on being able to find and mark nodes that are reachable from program variables.By tracing all descendants of such nodes and marking them as well, all cells not reachable from program variables may then be identified and collected.The list-creating function LIST of SLIP may be amended to mark those lists for which the programmer wishes to assume responsibility.Given this modification, a LISP-like garbage collector that recovers abandoned reentrant list structures may then be appended to the SLIP system.