Re: [Haskell-cafe] Best way to find an "undefined" error?

On Thu, Feb 14, 2008 at 3:02 PM, Denis Bueno wrote:

On Thu, Feb 14, 2008 at 2:55 PM, Don Stewart wrote:

...

You can use the profiler to get a stack trace, or use the new GHCi debugger to step backwards from the exception to the source.

I wrote a bit of a tutorial for this here:

http://cgi.cse.unsw.edu.au/~dons/blog/2007/11/14#no-exceptions

Section 6.3 of http://haskell.org/haskellwiki/Debugging also is relevant for using ghcu to step backward ... perhaps the section label is misleading, though. Feel free to modify as needed if you find the ghci stepper lets you find the problem

Well, when using +RTS -xc, I get: Prelude.undefined I'm not really sure what to do with this, not really the stacktrace I was hoping for. The ghci debugger I found was really quite nice, up until it his some portion of code that it isn't interpreting. By not "interpreting" i mean things that have been already been compiled and it's just calling (even if it has been compiled with profiling). I have a feeling that my problem is somewhere in something that has already been compiled. Knowing that, should +RTS -xc be giving me more information? Is there a way for it to do so? Regards, Scott