如何将GHC与不在当前工作目录中的阴谋集团沙箱一起使用? [英] How can I use GHC with a cabal sandbox that's not in the current working directory?

问题描述

如果我使用cabal sandbox init创建一个阴谋沙箱，则可以使用cabal repl或cabal exec ghc(i)来处理这些软件包，而无需创建项目:

If I create a cabal sandbox with cabal sandbox init, I can use cabal repl or cabal exec ghc(i) to work with those packages without creating a project:

$ mkdir /tmp/example && cd /tmp/example
$ cabal sandbox init
$ cabal install QuickCheck
$ cabal exec ghci
Prelude> :m Test.QuickCheck
Prelude Test.QuickCheck>

但是，如果我将路径更改为其他路径，甚至更改为子目录，那么我将无法再访问软件包:

However, if I change the path to something else, even to a subdirectory, I cannot access the packages anymore:

$ mkdir -p /tmp/example/sub && cd /tmp/example/sub
$ cabal exec ghci
Prelude> :m Test.QuickCheck
<no location info>:
    Could not find module ‘Test.QuickCheck’
    It is not a module in the current program, or in any known package.

是否可以使用沙箱中的内容而不复制其内容?

Is there any way to use the contents from the sandbox, without copying its content?

推荐答案

问题是cabal仅会尊重当前工作目录中的沙箱.但是，有几个选项可以为Cabal指定沙箱位置，也可以为GHC指定包装数据库.

The problem is that cabal will only respect sandboxes in the current working directory. However, there are several options where you can specify a sandbox location for cabal or the package databse for GHC.

您可以使用cabal的--sandbox-config-file选项来指定沙箱配置，例如

You can use cabal's --sandbox-config-file option to specify a sandbox configuration, e.g.

$ cabal --sandbox-config-file=/tmp/example/cabal.sandbox.config exec ghci
Prelude> :m Test.QuickCheck
Prelude Test.QuickCheck>   

这还使您能够从其他位置更改沙箱，如果您只想将随机内容安装到临时位置，这将非常方便:

This also enables you to change the sandbox from other places, which comes in handy if you just want to install random stuff into a temporary place:

$ cabal --sandbox-config-file=/tmp/example/cabal.sandbox.config install lens
$ cabal --sandbox-config-file=/tmp/example/cabal.sandbox.config repl
Prelude> :m Control.Lens
Prelude Control.Lens> :m Test.QuickCheck
Prelude Control.Lens Test.QuickCheck>

由于这会在一段时间后变得麻烦，您可能应该添加一个别名

Since this gets cumbersome after a while, you should probably add an alias

$ alias sandboxed-cabal="cabal --sandbox-config-file=/tmp/example/cabal.sandbox.config"
$ sandboxed-cabal repl
Prelude>

使用ghc -package-db

或者，当您将GHC与

Using ghc -package-db

Alternatively, you can directly specify the package database when you use GHC with -package-db:

$ ghci -package-db /tmp/example/.cabal-sandbox/<ARCH>-packages.conf.d
Prelude> :m Test.QuickCheck
Prelude Test.QuickCheck>

<ARCH>取决于您的系统和使用的GHC，例如在64位Linux和GHC 7.10.3上，它是x86_64-linux-ghc-7.10.3-packages.conf.d.然后，您可以使用该数据库中的所有软件包:

The <ARCH> depends on your system and the used GHC, e.g. on a 64bit Linux and GHC 7.10.3 it's x86_64-linux-ghc-7.10.3-packages.conf.d. You can then use all packages in that database:

$ ghci -package-db /tmp/example/.cabal-sandbox/<ARCH>-packages.conf.d
Prelude> :m Control.Lens
Prelude Control.Lens> 

同样，别名应该派上用场.

Again, an alias should come in handy.

最后但并非最不重要的一点是，您可以调整环境变量.但是，如果环境变量

Last, but not least, you can adjust an environment variable. However, if the environment variable GHC_PACKAGE_PATH exists, it will overwrite GHC's usual package databases, so you either need to check ghc-pkg list and add them too

$ GHC_PACKAGE_PATH=/opt/ghc/7.10.3/lib/ghc-7.10.3/package.conf.d/:/tmp/example/.cabal-sandbox/x86_64-linux-ghc-7.10.3-packages.conf.d ghci

或使用

or use -global-package-db and -user-package-db to reenable them:

$ GHC_PACKAGE_PATH=/tmp/example/.cabal-sandbox/x86_64-linux-ghc-7.10.3-packages.conf.d ghci -global-package-db -user-package-db

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