[Haskell-cafe] :Trace has no history

[Steve Severance]

How do I tell? Does this mean that if the exception is occurring in a
haskell library I can't get to it? I am trying to run down a
Prelude.read: No Parse error and I need to see the value that it is
failing to parse on.

Thanks.

Steve

On Tue, Aug 31, 2010 at 11:05 AM, Pepe Iborra <pepeiborra at gmail.com> wrote:
> Hi Steve
>
> The debugger only traces calls in interpreted code. Perhaps the call
> to myMethod is being made from object code?
>
> Admittedly, the ghci debugger can take some effort to learn to use
> properly. Make sure that you give a look to the ghc user guide if you
> haven't done so yet.
>
>
> Best,
> pepe
>
> On Tuesday, August 31, 2010, Steve <sseveran at gmail.com> wrote:
>> I am trying to debug a problem in GHCI. I invoke my method with trace
>> but when it breaks on exception i can't get this history. Output is
>> below. Thanks.
>>
>>
>> relude Symbols> :set -fbreak-on-exception
>> Prelude Symbols> :trace myMethod
>> Loading package HUnit-1.2.2.1 ... linking ... done.
>> Loading package syb-0.1.0.2 ... linking ... done.
>> Loading package base-3.0.3.2 ... linking ... done.
>> Loading package old-locale-1.0.0.2 ... linking ... done.
>> Loading package time-1.1.4 ... linking ... done.
>> Loading package random-1.0.0.2 ... linking ... done.
>> Loading package QuickCheck-1.2.0.0 ... linking ... done.
>> Loading package Decimal-0.1.0 ... linking ... done.
>> Loading package array-0.3.0.0 ... linking ... done.
>> Loading package Diff-0.1.2 ... linking ... done.
>> Loading package bytestring-0.9.1.5 ... linking ... done.
>> Loading package containers-0.3.0.0 ... linking ... done.
>> Loading package mtl-1.1.0.2 ... linking ... done.
>> Loading package old-time-1.0.0.3 ... linking ... done.
>> Loading package convertible-1.0.9 ... linking ... done.
>> Loading package utf8-string-0.3.4 ... linking ... done.
>> Loading package HDBC-2.2.6 ... linking ... done.
>> Loading package HDBC-mysql-0.6.3 ... linking ... done.
>> Loading package parsec-2.1.0.1 ... linking ... done.
>> Loading package network-2.2.1.7 ... linking ... done.
>> Loading package HTTP-4000.0.9 ... linking ... done.
>> Loading package binary-0.5.0.2 ... linking ... done.
>> Loading package digest-0.0.0.8 ... linking ... done.
>> Loading package filepath-1.1.0.3 ... linking ... done.
>> Loading package unix-2.4.0.0 ... linking ... done.
>> Loading package directory-1.0.1.0 ... linking ... done.
>> Loading package pretty-1.0.1.1 ... linking ... done.
>> Loading package zlib-0.5.2.0 ... linking ... done.
>> Loading package zip-archive-0.1.1.6 ... linking ... done.
>> Loading package Core-0.0.1 ... linking ... done.
>> Beginning Update
>> Stopped at <exception thrown>
>> _exception ::
>>  e = GHC.Exception.SomeException (GHC.Exception.D:Exception _
>>
>> (GHC.Show.D:Show ...) ....)
>>                                  (GHC.IO.Exception.IOError Nothing
>> GHC.IO.Exception.UserError ....)
>> [<exception thrown>] Prelude Symbols> :history
>> Empty history. Perhaps you forgot to use :trace?
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>>
>
> --
> -- José Iborra        http://www.dsic.upv.es/~jiborra
> -- UPV Valencia       Telf. (+34) 96 387 00 00 (ext) 83529
> -- Camino de Vera s/n. 46022 Valencia (Spain)
>



-- 
------------------------------------
Steve Severance
c. 240.472.9645
e. steve at medwizard.net
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