[index entries: _debug_ _debugger_ _debugging_ ]

_Calltrace_ is a tool that displays all calls to user procedures. It
 displays the arguments to the calls, and indents to show the depth of
 the continuation.

 Quick instructions
------------------

  0) Throw away .zo versions of your source

  1) Prefix your program with
      (require (lib "calltrace.ss" "trace"))

  2) Run your program

The calltrace module is odd; don't import it into another
module. Instead, the calltrace module is meant to be invoked from the
top-level, so that it can install an evaluation handler, exception
handler, etc.

To reuse parts of the code of errortrace, import
_calltrace-lib.ss_. It contains all of the names here but
does not set the eval-handler.

Exception Information
---------------------

Invoking the calltrace.ss module sets the eval handler to instrument
Scheme source code.

 NOTE: errortrace has no effect on code loaded as compiled byte code
 (i.e., from a .zo file) or native code (i.e., from a .dll or .so
 file).

Errortrace's instrumentation can be explicitly disabled via the
`instrumenting-enabled' boolean parameter. Instrumentation is on by
default. The `instrumenting-enabled' parameter affects only the way
that source code is compiled, not the way that exception information
is reported.

> (instrumenting-enabled) - returns #t if error tracing instrumentation is
  enabled, #f otherwise
> (instrumenting-enabled on?) - enables/disables error tracing
  instrumentation

<slowdown information elided.>

Do not load calltrace before writing .zo files. Calltrace
instruments S-expressions with unprintable values; this works fine if
the instrumented S-expression is passed to the default eval handler,
but neither the S-expression nor its byte-code form can be marshalled
to a string.