On 20/10/2009 14:54, Ralph Crawford wrote:
Hi. I'm working with GHC 6.10.4 on Solaris. I'm new at Haskell and
have inherited a rather large and complex program to maintain and
modify. I'd like to get a listing of everything - every single step -
that's done in a run of the program. Something similar to the output of
the :step command, but I'd like the entire run (which would involve tens
of thousands of steps). Is there a way to just do this - have it run
and print everything it does to the screen?
I've tried doing the following, after starting a "script" to capture all
of the screen output...
ghci -fglasgow-exts parsequery.hs
:break 36
main
which takes me to this prompt...
Loading package mtl-1.1.0.2 ... linking ... done.
Stopped at lesearch.hs:36:13-39
_result :: IO SearchState = _
input :: [String] = _
st :: SearchState = _
[lesearch.hs:36:13-39] *Main>
This takes me to the call before the one that I want to output each step
of so that I can then manually, with hardcopy, read it and get an idea
of what happened.
So I start a step through the next call.
[lesearch.hs:36:13-39] *Main> :step process_query_loop st input
Stopped at lesearch.hs:(46,0)-(69,39)
_result :: IO SearchState = _
... [lesearch.hs:(46,0)-(69,39)] *Main>
So far so good. This is what I want to see - a listing like this for
every (interpreted of course) line of haskell code that runs, all the
way to the end. Since this is a very large program, at this point I
started pasting this to the terminal - 4 steps at a time...
:step
:step
:step
:step
This gave me the listing I wanted. But after a certain point, it
inevitably fails with a core dump, and what I capture from the screen is
garbled up to that point anyway. I'm hoping there's a simpler way to do
this. Thanks for taking the time to read this.
If you get a core dump, that's obviously a bug. If you can supply us
with a small program that illustrates the bug, please submit a bug
report at
http://hackage.haskell.org/trac/ghc/wiki/ReportABug
As for getting a list of the evaluation steps, we don't have anything
that does exactly what you want at the moment, but it probably wouldn't
be hard to implement on top of the existing debugging functionality.
Feel free to make a feature request, describing exactly what
functionality you'd like to see:
http://hackage.haskell.org/trac/ghc/newticket?type=feature+request
Cheers,
Simon
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