the impossible happened

[Malcolm Wallace]

"Simon Peyton-Jones" <simonpj at microsoft.com> writes:

> A difficulty is that the caller of 'head' might itself be called from
> somewhere else:
> 
> 	foo (xs, ys) = head xs
> 
> It's all very like cost-centre stacks, which is why GHC provides the -xc
> option when you are profiling.  I think that give you what you want ---
> but you have to compile your program profiled.

Just a reminder that tracing with Hat is yet another way to get
the complete call-stack (virtualised as if it had been evaluated
strictly).  But, like -xc requires you to recompile for profiling,
Hat also requires a recompilation for tracing.

Regards,
    Malcolm