Enhancement: Default cabal to `-p` profiling enabled

Andrew Pennebaker andrew.pennebaker at gmail.com
Thu Jul 24 20:30:19 UTC 2014

What if -p continued to default to false, but when -p was specified, cabal
was smart enough to automatically recompile all dependencies with -p,
rather than complaining about them lacking profiling?

On Thu, Jul 24, 2014 at 12:51 PM, Alois Cochard <alois.cochard at gmail.com>

> Hi Andrew,
> I'm actually writing a tool to automate the workflow when coding on
> multiple modules, and dealing with a shared sandbox.
> I think that would be the perfect fit for an option like this (and thanks
> to your email, I'll be sure it's easy to enable... or maybe even make it
> the default... but ... developers often want fast compilation too!), I
> don't really see that enabled by default on cabal for the same reason
> others mentioned.
> Cheers
> On 24 July 2014 00:18, Andrew Pennebaker <andrew.pennebaker at gmail.com>
> wrote:
>> I love GHC's profiling support, and like to use it to analyze the
>> performance of my Haskell applications. However, profiling an application
>> is difficult when it depends on any third-party libraries, as cabal doesn't
>> include profiling information by default.
>> Fortunately, cabal can reinstall a library with profiling support, with:
>> cabal install --reinstall -p <library>
>> Unfortunately, cabal is a bit of a simpleton, so this will fail unless
>> that libraries dependencies are also installed with profiling enabled:
>> cabal install --reinstall -p <libraryX> <libraryY> <libraryZ> ...
>> For example, a user who wants to profile his die-rolling program must run:
>> $ sudo apt-get install haskell-platform haskell-platform-doc
>> haskell-platform-prof
>> $ sudo cabal install --reinstall -p mwc-random rvar random-fu
>> random-source mersenne-random-pure64 stateref flexible-defaults th-extras
>> MonadPrompt math-functions erf vector-th-unbox monad-loops random-shuffle
>> MonadRandom
>> And that long list of packages must be slowly grown one at a time,
>> starting from random-source, based on many attempts at running cabal
>> install --reinstall -p ..., waiting several minutes for compilation to
>> partially complete, and scrolling back up through the logs to track down
>> which dependencies also neglected to compile with profiling enabled.
>> It can take a while to get a list of this long, full dependency chain. It
>> would be much easier if cabal simply enabled `-p` by default, so we didn't
>> have to think about it.
>> What do you think?
>> --
>> Cheers,
>> Andrew Pennebaker
>> www.yellosoft.us
>> _______________________________________________
>> Libraries mailing list
>> Libraries at haskell.org
>> http://www.haskell.org/mailman/listinfo/libraries
> --
> *A\ois*
> http://twitter.com/aloiscochard
> http://github.com/aloiscochard


Andrew Pennebaker
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