[Haskell-beginners] best way to proceed with package install

Miguel Negrao miguel.negrao-lists at friendlyvirus.org
Tue Oct 30 19:54:31 CET 2012

A 30/10/2012, às 09:33, Chaddaï Fouché escreveu:

> There is some good explanations of that phenomenon around under the
> name "Butterfly effect" like :
> http://cdsmith.wordpress.com/2011/01/17/the-butterfly-effect-in-cabal/
> This is really painful when you start to have accumulated a number of
> packages, and the more dependencies, the more likely you are to hit
> this...
> Which is why most people now recommend using sandboxes for
> installations, to allows you to have several different packages
> database and not have to scratch your whole GHC installation once
> you've damaged it (there are always alternative to this radical step,
> but it takes more time than restarting from zero so nobody use them).
> Basically, as soon as you hit a problem with a cabal installation that
> would require a reinstall, you restart from a new sandbox. The
> solutions to do that are virthualenv, capri or cabal-dev and the next
> release of cabal itself should have a sandbox mode.
> The proper solution would be to allow several version of the same
> package version to cohabit but that's pretty complicated and not yet
> possible.

After reading that post and a couple others I tried to install cabal-dev which is supposed to help with some of these issues. Ironically it doesn’t install either...

miguelnegrao at Mac-Miguel:~$ cabal install cabal-dev
Resolving dependencies...
[1 of 1] Compiling Main             ( /var/folders/ps/fvzyp6yj5k743k1clpmt24kw0000gn/T/cabal-dev-0.9.1-11243/cabal-dev-0.9.1/Setup.hs, /var/folders/ps/fvzyp6yj5k743k1clpmt24kw0000gn/T/cabal-dev-0.9.1-11243/cabal-dev-0.9.1/dist/setup/Main.o )
Linking /var/folders/ps/fvzyp6yj5k743k1clpmt24kw0000gn/T/cabal-dev-0.9.1-11243/cabal-dev-0.9.1/dist/setup/setup ...
ld: warning: could not create compact unwind for _ffi_call_unix64: does not use RBP or RSP based frame
unrecognized option `--disable-benchmarks'
Failed to install cabal-dev-0.9.1
cabal: Error: some packages failed to install:
cabal-dev-0.9.1 failed during the configure step. The exception was:
ExitFailure 1

miguelnegrao at Mac-Miguel:~$ cabal -V
cabal-install version
using version of the Cabal library 

Is this a lost cause ? :-)


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