我无法让这个导入在haskell中工作。
import Network.HTTP.Conduit
当我尝试编译时，我收到以下错误：
$ 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.
如果我尝试在GHCI中加载文件，则会出现同样的错误。
我已通过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
如果它可能有所作为，我使用的是Ubuntu 12.04。
为什么这不会导入任何想法？
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，'ghc-pkg list http-conduit'中的警告不再出现，但问题并未解决。
从'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'进行编译时的输出：
$ 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
似乎我确实列出了所有依赖项。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是依赖列表中的每个包，这些包是使用'-package http-conduit'标志进行编译的：
/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:
答案 0 :(得分：8)
我无法直接解决问题。但是，我能够“核对”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，它运作良好。您还必须重新安装所有其他软件包。
答案 1 :(得分：0)
FWIW 我使用了“cabal install http-conduit” 然后我得到以下提示：
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 中得到这个：
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”解决了这个问题。