Haskell Impossibile trovare il modulo `Network.HTTP.Conduit '

Question

Non riesco a far funzionare questa importazione in haskell.

import Network.HTTP.Conduit 

Quando provo a compilare ricevo il seguente errore:

$ ghc Play.hs 

Play.hs:1:8: 
    Could not find module `Network.HTTP.Conduit' 
    Use -v to see a list of the files searched for. 

Lo stesso errore si verifica se provo a caricare il file in GHCI.

Ho installato l'ultima versione di http-conduit tramite cabal. Ecco l'output dalla cabala:

$ cabal -list http-conduit 
* http-conduit 
    Synopsis: HTTP client package with conduit interface and HTTPS support. 
    Default available version: 1.8.2 
    Installed versions: 1.6.0.4, 1.8.2 
    Homepage: http://www.yesodweb.com/book/http-conduit 
    License: BSD3 

* http-conduit-browser 
    Synopsis: Browser interface to the http-conduit package 
    Default available version: 1.6.3 
    Installed versions: 1.6.3 
    Homepage: https://github.com/exbb2/http-conduit-browser 
    License: BSD3 

Se può fare la differenza, sto usando Ubuntu 12.04.

Qualche idea sul perché questo non verrà importato?

Edit: uscita dalla 'lista GHC-pkg':

$ ghc-pkg list http-conduit 
WARNING: there are broken packages. Run 'ghc-pkg check' for more details. 
/var/lib/ghc/package.conf.d 
    http-conduit-1.6.0.4 
    http-conduit-1.8.2 
~/.ghc/i386-linux-7.4.1/package.conf.d 

E da 'controllo GHC-pkg':

$ ghc-pkg check 
The following packages are broken, either because they have a problem 
listed above, or because they depend on a broken package. 
derive-2.5.11 
derive-2.5.11 
peakachu-0.3.0 
peakachu-0.3.0 

Dopo l'esecuzione di 'GHC-pkg annullare la registrazione derivare-2.5. 11 'e' ghc-pkg annullano la registrazione di peakachu-0.3.0 'gli avvertimenti di' ghc-pkg list http-conduit 'non si verificano più ma il problema non viene risolto.

Dal stderr di 'controllo GHC-pkg':

Warning: haddock-interfaces: /usr/local/share/doc/http-conduit-browser-1.6.3/html/http-conduit-browser.haddock doesn't exist or isn't a file 
Warning: haddock-html: /usr/local/share/doc/http-conduit-browser-1.6.3/html doesn't exist or isn't a directory 
Warning: haddock-interfaces: /usr/local/share/doc/http-conduit-1.8.2/html/http conduit.haddock doesn't exist or isn't a file 
Warning: haddock-html: /usr/local/share/doc/http-conduit-1.8.2/html doesn't exist or isn't a directory 

uscita quando si compila con '-package http-conduit':

$ ghc -package http-conduit Play.hs -v 
<command line>: cannot satisfy -package http-conduit: 
    http-conduit-1.8.2-13f7764675fbae0ac9de8bcf7925f78e is unusable due to missing or recursive dependencies: 
     asn1-data-0.7.1-cb75ffc05237f33632b42d2fb76a7a29 attoparsec-conduit-0.5.0.1-5fe0cc7293ce100ae00db2d7e67f682f blaze-builder-conduit-0.5.0.1-59a72b475661fd25bd4619f58e8b40de certificate-1.3.1-dd3ba477e9b28bd6e4ab3d8865f22a87 conduit-0.5.2.4-88846c185b7e5037f242975916feb7e2 failure-0.2.0.1-49a74d2d91efe8118b3ce4233a86c2be lifted-base-0.1.2-1905d9349e322d5bbdfc585c7291efe4 monad-control-0.3.1.4-2629785f64d5c6eb4b6a72e854127870 network-2.4.0.1-53e0509d073f1b67ec3e641af74cb551 resourcet-0.4.0.1-07b5b503a019bd31b56feec9c26dfaec tls-1.0.1-f578324e807426668353637611a71070 tls-extra-0.5.0-459144227bb52a8255b4a149f58f3520 transformers-base-0.4.1-d27396afe6939ffd84456ceebf04bfbb zlib-conduit-0.5.0.1-f6b2f2e99cffe03ace3d731c20826f12 
http-conduit-1.6.0.4-963a389e596e9c9f7c021dc97238cc52 is unusable due to missing or recursive dependencies: 
    asn1-data-0.7.1-cb75ffc05237f33632b42d2fb76a7a29 attoparsec-conduit-0.5.0.1-5fe0cc7293ce100ae00db2d7e67f682f blaze-builder-conduit-0.5.0.1-59a72b475661fd25bd4619f58e8b40de certificate-1.2.8-78aa58c1d97c0315f599845cf7924ae2 conduit-0.5.2.4-88846c185b7e5037f242975916feb7e2 failure-0.2.0.1-49a74d2d91efe8118b3ce4233a86c2be lifted-base-0.1.2-1905d9349e322d5bbdfc585c7291efe4 monad-control-0.3.1.4-2629785f64d5c6eb4b6a72e854127870 network-2.4.0.1-53e0509d073f1b67ec3e641af74cb551 resourcet-0.4.0.1-07b5b503a019bd31b56feec9c26dfaec tls-0.9.10-bedda6ba89d62d8b86895a07b0d4437e tls-extra-0.4.6-e10848dbad24b59704ecb96d86e5362a transformers-base-0.4.1-d27396afe6939ffd84456ceebf04bfbb zlib-conduit-0.5.0.1-f6b2f2e99cffe03ace3d731c20826f12 

Sembra che io ho tutte le dipendenze elencate. Ecco l'output 'elenco cabal'

* asn1-data 
Synopsis: ASN1 data reader and writer in RAW, BER and DER forms 
Default available version: 0.7.1 
Installed versions: 0.7.1 
Homepage: http://github.com/vincenthz/hs-asn1-data 
License: BSD3 

* attoparsec-conduit 
Synopsis: Consume attoparsec parsers via conduit. 
Default available version: 0.5.0.2 
Installed versions: 0.5.0.1 
Homepage: http://github.com/snoyberg/conduit 
License: BSD3 

* blaze-builder-conduit 
Synopsis: Convert streams of builders to streams of bytestrings. 
Default available version: 0.5.0.1 
Installed versions: 0.5.0.1 
Homepage: http://github.com/snoyberg/conduit 
License: BSD3 

* certificate 
Synopsis: Certificates and Key Reader/Writer 
Default available version: 1.3.1 
Installed versions: 1.2.8, 1.3.1 
Homepage: http://github.com/vincenthz/hs-certificate 
License: BSD3 

* conduit 
Synopsis: Streaming data processing library. 
Default available version: 0.5.2.7 
Installed versions: 0.5.2.4 
Homepage: http://github.com/snoyberg/conduit 
License: BSD3 

* failure 
Synopsis: A simple type class for success/failure computations. 
Default available version: 0.2.0.1 
Installed versions: 0.2.0.1 
Homepage: http://www.haskell.org/haskellwiki/Failure 
License: BSD3 

* lifted-base 
Synopsis: lifted IO operations from the base library 
Default available version: 0.2 
Installed versions: 0.1.2 
Homepage: https://github.com/basvandijk/lifted-base 
License: BSD3 

* monad-control 
Synopsis: Lift control operations, like exception catching, through monad 
      transformers 
Default available version: 0.3.1.4 
Installed versions: 0.3.1.4 
Homepage: https://github.com/basvandijk/monad-control 
License: BSD3 

* network 
Synopsis: Low-level networking interface 
Default available version: 2.4.0.1 
Installed versions: 2.4.0.1 
Homepage: https://github.com/haskell/network 
License: BSD3 

* resourcet 
Synopsis: Deterministic allocation and freeing of scarce resources. 
Default available version: 0.4.0.2 
Installed versions: 0.4.0.1 
Homepage: http://github.com/snoyberg/conduit 
License: BSD3 

* tls 
Synopsis: TLS/SSL protocol native implementation (Server and Client) 
Default available version: 1.0.1 
Installed versions: 0.9.10, 1.0.1 
Homepage: http://github.com/vincenthz/hs-tls 
License: BSD3 

* tls-extra 
Synopsis: TLS extra default values and helpers 
Default available version: 0.5.0 
Installed versions: 0.4.6, 0.4.6, 0.5.0, 0.5.0 
Homepage: http://github.com/vincenthz/hs-tls 
License: BSD3 

* transformers-base 
Synopsis: Lift computations from the bottom of a transformer stack 
Default available version: 0.4.1 
Installed versions: 0.4.1 
Homepage: https://github.com/mvv/transformers-base 
License: BSD3 

* zlib-conduit 
Synopsis: Streaming compression/decompression via conduits. 
Default available version: 0.5.0.1 
Installed versions: 0.5.0.1 
Homepage: http://github.com/snoyberg/conduit 
License: BSD3 

Questa è l'uscita dal 'elenco ghc-pkg xxxx' dove xxxx è ciascuno dei pacchetti nella lista dipendenze risultanti dalla compilazione con '-package http-condotto 'flag:

/var/lib/ghc/package.conf.d: 
asn1-data-0.7.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

/var/lib/ghc/package.conf.d: 
attoparsec-conduit-0.5.0.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

/var/lib/ghc/package.conf.d: 
blaze-builder-conduit-0.5.0.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

/var/lib/ghc/package.conf.d: 
certificate-1.2.8 
certificate-1.3.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

/var/lib/ghc/package.conf.d: 
conduit-0.5.2.4 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

/var/lib/ghc/package.conf.d: 
failure-0.2.0.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 
failure-0.2.0.1 

/var/lib/ghc/package.conf.d: 
lifted-base-0.1.2 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

/var/lib/ghc/package.conf.d: 
monad-control-0.3.1.4 

~/.ghc/i386-linux-7.4.1/package.conf.d: 
monad-control-0.3.1.4 

/var/lib/ghc/package.conf.d: 
network-2.4.0.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 
network-2.4.0.1 

/var/lib/ghc/package.conf.d: 
resourcet-0.4.0.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

/var/lib/ghc/package.conf.d: 
tls-0.9.10 
tls-1.0.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

/var/lib/ghc/package.conf.d: 
tls-extra-0.4.6 
tls-extra-0.5.0 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

/var/lib/ghc/package.conf.d: 
transformers-base-0.4.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 
transformers-base-0.4.1 

/var/lib/ghc/package.conf.d: 
zlib-conduit-0.5.0.1 

~/.ghc/i386-linux-7.4.1/package.conf.d: 

Answer 1

Non è stato possibile risolvere il problema direttamente. Ma, sono stato in grado di "nuke" i pacchetti installati e ricominciare da capo.

rm -rf ~/.ghc/i386-linux-7.4.1 
cabal install http-conduit 

Dopo questo, ha funzionato bene. Dovrai reinstallare anche tutti gli altri pacchetti.