10 The HCL Package

trace-print-circle

Variable

Summary

Controls how circular structure are printed in trace output.

Package

hcl

Initial Value

nil

Description

*trace-print-circle* controls how circular structures are printed during output from tracing. It allows the printing of circular structures by the tracer to be controlled independently of the usual printing mechanism, which is governed by*print-circle*.*print-circle* is bound to the value of*trace-print-circle* while printing tracing information.

Example

USER 19 > (setq *trace-print-circle* t)

T 
USER 20 > (defun circ (l)
           (rplacd (last l) l)
          l)

CIRC 
USER 21 > (trace second)

SECOND 
USER 22 > (second (circ '(1 2 3 4)))
0 SECOND > (#1=(1 2 3 4 . #1#)) 
0 SECOND < (2) 2

Notes

*trace-print-circle* is an extension to Common Lisp.

See also

trace