set the trace evisc tuple
Major Section:  TRACE

A trace evisc-tuple, which is set by this utility, provides a means to restrict printing during tracing. See evisc-tuple for an introduction to evisc-tuples; also see set-evisc-tuple and see set-iprint.

By default the ACL2 trace mechanism, trace$, automatically deals with stobjs, the logical world, and certain other large structures. See trace$, in particular the documentation of trace$ option :hide. However, even with that default behavior you may want to restrict what is printed according to the print-level and print-length of an evisc-tuple; see evisc-tuple.


; Set trace evisc tuple to a standard value, using current Lisp *print-level*
; and *print-length* variables:
(set-trace-evisc-tuple t state)

; Set trace evisc tuple back to its default:
(set-trace-evisc-tuple nil state)

; Set trace evisc tuple to restrict print-level to 3 and print-length to 4,
; while hiding the logical world and suitably printing stobjs even if trace$
; option ``:hide nil'' is used.  (Note: calling trace-evisceration-alist
; directly requires removing this function as `untouchable', which requires a
; trust tag; see remove-untouchable.)
 (evisc-tuple 3 4 (trace-evisceration-alist state) nil)

General Forms:

(set-trace-evisc-tuple nil state) ; trace evisc-tuple set to standard value
(set-trace-evisc-tuple   t state) ; trace evisc-tuple set to hide the logical
                                  ;   world and deal with stobjs even when
                                  ;   trace$ option ``:hide nil'' is supplied
(set-trace-evisc-tuple evisc-tuple state)
                                  ; tracing set to use indicated evisc-tuple

See trace$ for a discussion of ACL2 tracing. The evisc-tuple used by that trace utility is the one last installed by set-trace-evisc-tuple (or by set-evisc-tuple for the trace-evisc-tuple) -- initially to the default of nil -- unless overriden by trace option :evisc-tuple.

Remark. If you use value t, then ACL2 will ensure that the logical world and stobjs are kept up-to-date in the trace evisc-tuple.