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Haskell无法找到模块`Network.HTTP.Conduit`。

httphaskellnetworkinghttpshttp-conduit
7
我无法在Haskell中让这个导入模块正常工作。
import Network.HTTP.Conduit

当我尝试编译时，出现以下错误：

$ 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，会出现相同的错误。

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

如果有影响的话，我使用的是Ubuntu 12.04操作系统。
为什么无法导入？你有任何想法吗？
编辑： 'ghc-pkg list' 命令的输出：
$ 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

并且来自 '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

在运行 'ghc-pkg unregister derive-2.5.11' 和 'ghc-pkg unregister peakachu-0.3.0' 后，'ghc-pkg list http-conduit' 的警告不再出现，但问题仍未解决。
从 'ghc-pkg check' 的 stderr 中可以看到：
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”编译时的输出结果:

$ 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

看起来我已经列出了所有的依赖项。这是从'cabal list'输出的结果。

* 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

这是使用“-package http-conduit”标志编译的依赖项列表中的每个软件包所生成的“ghc-pkg list xxxx”的输出：
/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:
我正在使用版本7.4.1。这是通过apt-get install ghc安装的版本。 - Joe
1
好的，那就不是那个问题。ghc-pkg list http-conduit 的输出是什么？ - Daniel Fischer
啊，这看起来很有前途。我已经更新了原帖并附上了输出结果。 - Joe
ghc-pkg check 有进一步的输出吗？ - Daniel Fischer
在编译并指定 -package http-conduit 时，似乎缺少两个版本的 http-conduit 的某些依赖项。我已经将输出添加在上面了。 - Joe
显示剩余8条评论
2个回答
10

我无法直接解决这个问题。但是，我能够“核弹”安装的软件包并重新开始。

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

之后，它能够正常工作。您还需要重新安装所有其他软件包。

我建议学习使用Cabal沙盒http://coldwa.st/e/blog/2013-08-20-Cabal-sandbox.html - 自从使用它们后，我很少再需要清空我的.ghc目录了。 - ErikR
0

顺便说一下，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，但在ghc中得到了这个：

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”可以解决这个问题。
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