哈斯克尔找不到模块`Network.HTTP.Conduit‘

Question

我不能让这个导入在haskell中工作。

import Network.HTTP.Conduit

当我尝试编译时，我得到了以下错误：

$ 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.

如果我试图在GHCI中加载文件，同样的错误也会发生。

我已经通过cabal安装了最新版本的http-conduit。以下是cabal的输出：

$ 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

如果可能会有所不同，我使用的是Ubuntu 12.04。

你知道为什么这个不能导入吗？

编辑：'ghc-pkg list‘的输出：

$ 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

来自'ghc-pkg check'：

$ 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

运行'ghc-pkg unregister derive 2.5.11‘和'ghc-pkg unregister peakachu-0.3.0’后，来自'ghc-pkg list http-conduit‘的警告不再出现，但该问题未修复。

来自'ghc-pkg check‘的stderr：

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

使用'-package http-conduit‘编译时的输出：

$ 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

看起来我确实列出了所有的依赖项。这是'cabal list‘的输出

* 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

这是'ghc-pkg list xxxx‘的输出，其中xxxx是使用'-package http-conduit’标志编译产生的依赖项列表中的每个包：

/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

我不能直接解决这个问题。但是，我能够“核化”已安装的软件包并重新开始。

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

在此之后，它工作得很好。您还必须重新安装所有其他软件包。

Answer 2

FWIW我使用了"cabal install http-conduit“，然后我得到了以下提示：

Building     http-conduit-2.3.8 (lib)
Installing   http-conduit-2.3.8 (lib)
Completed    http-conduit-2.3.8 (lib)
Warning:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: Installation might not be completed as desired! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Without flags, the command "cabal install" doesn't expose libraries in a
usable manner. You might have wanted to run "cabal install --lib http-conduit".

然后我尝试加载我的文件，并在ghc中获得了以下内容：

Prelude> :l Main.hs
[1 of 1] Compiling Main             ( Main.hs, interpreted )

Main.hs:9:1: error:
    Could not load module ‘Network.HTTP.Conduit’
    It is a member of the hidden package ‘http-conduit-2.3.8’.
    You can run ‘:set -package http-conduit’ to expose it.
    (Note: this unloads all the modules in the current scope.)
    Use -v (or `:set -v` in ghci) to see a list of the files searched for.
  |
9 | import Network.HTTP.Conduit (simpleHttp)
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Failed, no modules loaded.

所以"cabal install --lib http-conduit“解决了这个问题。