Andy writes:
What I want is gdb for GHC :-) Perhaps another build (like profiling vs optimizer), and when you press ^C, the ghcdb> prompt comes up :-)
Hey, we already have pretty-much exactly that in nhc98. :-)
I wonder if the Cost Center Stack idea can be combined some debugging concepts, giving an approximation to a stack dump, and you can print (using a non evaluating print) the stack?
Hey, we already have pretty-much exactly that in nhc98. :-) The new improved Hat now has several different debugging tools. hat-stack gives a stack dump hat-observe shows some or all actual uses of a function (cf. HOOD) hat-detect automated algorithmic debugging (cf. Freja) hat-trail the classic redex-trails browser (cf. "old" Hat) There are also "tunnels" between the latter three tools, so you can for instance jump from a dodgy observation straight into an algorithmic debugging session starting at the suspicious point. hat-observe is about the nearest thing to a gdb I can imagine in a lazy pure setting. For you ghc junkies out there, yes we are currently developing a compiler-independent version of Hat which should give you identical tracing facilities in ghc as in nhc98, at least for the Haskell'98 language. The port is very much in its early stages though, so if you want to try the Hat tools out and give us your feedback on whether they meet your needs, we would prefer that you don't wait for the compiler-portable version, but recommend using nhc98 for the moment. I expect to make a new release with some improvements to the tools within the next couple of weeks. Regards, Malcolm