have no context information attached to them. Finding which
particular call to <literal>head</literal> in your program resulted in
the error can be a painstaking process, usually involving
- <literal>Debug.Trace.trace</literal>.</para>
+ <literal>Debug.Trace.trace</literal>, or compiling with
+ profiling and using <literal>+RTS -xc</literal> (see <xref
+ linkend="prof-time-options" />).</para>
<para>The GHCi debugger offers a way to hopefully shed some light on
these errors quickly and without modifying or recompiling the source