在Haskell Stack项目中构建yesod/amazonka依赖关系时遇到麻烦

Question

我试图在使用同样优秀的web框架耶索德构建的API的后端部分使用优秀的AWS 耶索德，但我很难使这两个库的依赖关系协同工作。

我用脚手架开始了yesod项目

stack new my-project yesod-mongo

它用yesod的最新版本(1.6.0)填充了我的阴谋文件。天真地将依赖项amazonka-core和amazonka-ssm (例如)添加到我的cabal文件中

Error: While constructing the build plan, the following exceptions were encountered:

In the dependencies for my-project-0.0.0:
    amazonka-core must match -any, but the stack configuration has no specified version
              (latest matching version is 1.5.0)
    amazonka-ssm must match -any, but the stack configuration has no specified version
             (latest matching version is 1.5.0)
needed since my-project is a build target.

正如建议的那样，我尝试将amazonka-core-1.5.0和amazonka-ssm-1.5.0添加到extra-deps下的stack.yaml文件中，但这不起作用：

Warning: WARNING: /home/ubuntu/my-project/my-project.cabal was modified manually.
     Ignoring package.yaml in favor of cabal file. If you want to use package.yaml
     instead of the cabal file, then please delete the cabal file.

Error: While constructing the build plan, the following exceptions were encountered:

In the dependencies for amazonka-core-1.5.0:
    conduit-1.3.0.2 from stack configuration does not match >=1.1 && <1.3 (latest
                matching version is 1.2.13.1)
needed due to my-project-0.0.0 -> amazonka-core-1.5.0

经过深入研究，yesod模板构建的快照似乎是基于islts-11.6构建的，但最新的快照是包含在其中的amazonka库是lts-10.9。因此，我再次尝试从yesod-mongo模板构建该项目，但这次指定了一个旧的快照：

ubuntu:~$ stack new my-project yesod-mongo --resolver lts-10.9
Downloading template "yesod-mongo" to create project "my-project" in my-project/ ...
Looking for .cabal or package.yaml files to use to init the project.
Using cabal packages:
- my-project/

Selected resolver: lts-10.9
Resolver 'lts-10.9' does not have all the packages to match your requirements.
    classy-prelude version 1.3.1 found
        - my-project requires ==1.4.*
    classy-prelude-conduit version 1.3.1 found
        - my-project requires ==1.4.*
    classy-prelude-yesod version 1.3.1 found
        - my-project requires ==1.4.*
    http-conduit version 2.2.4 found
        - my-project requires ==2.3.*
    persistent version 2.7.1 found
        - my-project requires ==2.8.*
    persistent-mongoDB version 2.6.0 found
        - my-project requires ==2.8.*
    yesod version 1.4.5 found
        - my-project requires ==1.6.*
    yesod-auth version 1.4.21 found
        - my-project requires ==1.6.*
    yesod-core version 1.4.37.3 found
        - my-project requires ==1.6.*
    yesod-form version 1.4.16 found
        - my-project requires ==1.6.*
    yesod-static version 1.5.3.1 found
        - my-project requires ==1.6.*
    Using package flags:
        - my-project: dev = False, library-only = False

现在我茫然不知所措，多了一点挫折。似乎模板忽略了快照规范。所以，我的问题是：

是否有方法从使用特定快照填充阴谋和stack.yaml文件的模板构建脚手架站点？我还能做些什么让这件事起作用吗？

如果有用的话，很乐意提供更多的信息。

编辑：我也尝试在上面的代码段中降低包的版本，虽然这解决了构建依赖关系的问题，但是现在这个脚手架站点没有编译(大概是因为事情已经从yesod-1.4.5变成yesod-1.6.0了)。

Answer 1

不幸的是，到目前为止，您不能使用带有yesod和amazonka的商业Haskell's堆栈模板。原因是：

• 最近在1.3版中重写了一个管道
• Some breaking changes were introduced in recent Yesod 1.6 which depends on conduit >= 1.3
• Amazonka不适用于最近版本的导管

让它工作的唯一方法是切换回堆栈模板的旧版本(那些模板实际上与堆栈解析器10.9一起工作)，然后使用这些模板创建一个新项目。幸运的是，Stack支持自定义堆栈模板：

$ stack new my-project https://raw.githubusercontent.com/github-user-id/stack-templates/master/my-template.hsfiles