如何将依赖项集成到Haskell中的现有项目中? [英] How to integrate dependency into existing project in Haskell?

问题描述

我目前正在尝试开始使用Haskell，因为我想使用 Pandoc 的部分代码库用于其他项目.由于我是Haskell的新手，因此我需要适当的IDE功能，例如代码完成和跳转到定义 AND 类型信息和悬停文档.我选择了带有 Haskell扩展名的VSCode.现在出现了我的问题:Pandoc依赖于 pandoc-types ，它是代码的组成部分，我需要了解和修改.但是使用 ghc-option "$ everything":-haddock (根据

I am currently trying to get started with Haskell because I want to use parts of the code base of Pandoc for a different project. Since I am new to Haskell I need proper IDE features like code completion and jump to definition AND type information and documentation on hover. I chose VSCode with the Haskell extension for the job. Now comes my problem: Pandoc depends on pandoc-types which is an integral part of the code, which I need to understand and modify. But using the ghc-option "$everything": -haddock (which should be the right way to achieve my goal according to this) does not seem to give me proper type information and documentation on hover. Since I copied the entire repo and do not intend to pull or push from the original repos I would like to add the code from pandoc-types to the existing Haskell code in the main pandoc repo.

因此，我尝试的一部分工作是下载 pandoc-types ，将 .hs 文件移动到 pandoc 中的相应目录中，并添加模块删除 .cabal 文件，同时从 .cabal 文件和 stack.yaml中删除 pandoc-< version> 依赖性.但是我在构建时遇到了兼容性错误:

So part of what I have tried was downloading pandoc-types moving the .hs files into the according dir in pandoc, adding the modules to the .cabal file while removing the pandoc-<version> dependency from the .cabal file and the stack.yaml. But all I got where compatibility errors when building:

➜  pandoc git:(master) ✗ stack build

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

In the dependencies for citeproc-0.1.0.1:
    pandoc-types-1.17.6 from stack configuration does not match >=1.22 && <1.23  (latest matching version is 1.22)
needed due to pandoc-2.11.0.1 -> citeproc-0.1.0.1

In the dependencies for commonmark-pandoc-0.2.0.1:
    pandoc-types-1.17.6 from stack configuration does not match >=1.21 && <1.23  (latest matching version is 1.22)
needed due to pandoc-2.11.0.1 -> commonmark-pandoc-0.2.0.1

In the dependencies for texmath-0.12.0.3:
    pandoc-types-1.17.6 from stack configuration does not match >=1.20 && <1.23  (latest matching version is 1.22)
needed due to pandoc-2.11.0.1 -> texmath-0.12.0.3

Some different approaches to resolving this:

  * Set 'allow-newer: true' in /Users/johannes/.stack/config.yaml to ignore all version constraints and build anyway.

  * Recommended action: try adding the following to your extra-deps in /Users/johannes/Programmieren/GITGOV/Pandocs/pandoc/stack.yaml:

- pandoc-types-1.22@sha256:15512ce011555ee720820f11cac0598317293406da5812337cbb1550d144e3bd,4071

Plan construction failed.

如何将依赖项的存储库更改为代码库的一部分.我尝试了几种不同的方法，但似乎没有任何效果.我对 GHC ， stack 和 cabal 甚至Haskell本身并不十分熟悉.还是有另一种方法可以使类型信息和悬停文件工作?特别是作为Haskell初学者，我确实需要此功能来正确掌握代码库.

How can I change a repo from a dependency be part of the code base. I have tried a few different things, but nothing seemed to work out. I am not really familiar with GHC, stack and cabal or even Haskell itself for that matter. Or is there another way to get the type information and documentation on hover working? Especially as a Haskell beginner I really need this functionality to properly grasp the code base.

也许也相关:

两个回购似乎都在构建过程中生成 Paths _ *.hs 文件.据我了解，它们还需要像提到的

Both repos seem to generate Paths_*.hs files in the building process. As far as I understand it, they also need to be copied into the src/ dir like mentioned here.

推荐答案

根据所使用的工具，有不同的处理方法.

Depending on the tool one uses there are different ways to go about it.

如果使用了 stack :

If stack is used:

按照此问题接受的答案在这里允许我通过 stack build 将 pandoc-types 作为本地依赖项来编译代码.

Following the accepted answer in this question here allows me to compile the code via stack build with pandoc-types as a local dependency.

如果使用 cabal :

If cabal is used:

与上述解决方案一样，需要将本地依赖项添加到存储库的根文件夹中.此外，应将对依赖项 cabal 文件的引用添加到 packages:部分中的 cabal.project 文件中，如下所示(这告诉cabal:还要编译此文件夹的内容):

As with the solution above one needs to add the local dependency into the root folder of the repo. Furthermore one should add a reference to the dependencies cabal file to the cabal.project file in the packages: section as follows (which tells cabal to also compile the contents of this folder):

packages: pandoc-types/pandoc-types.cabal pandoc.cabal

package pandoc
  flags: +embed_data_files -trypandoc
  ghc-options: -j +RTS -A64m -RTS

source-repository-package
    type: git
    location: https://github.com/jgm/citeproc
    tag: 0.1.0.1

<项目名称> .cabal 中的依赖项也需要删除版本限制.因此，文件已更改为:

Also the dependencies in the <projectname>.cabal need the version restrictions removed. So the file is changed from this:

library
  build-depends: pandoc-types          >= 1.22     && < 1.23

...对此:

library
  build-depends: pandoc-types

现在，我的代码使用 cabal build 进行编译.

Now my code compiles with cabal build.

但是，我的问题仍然存在.当遵循这两种方法时，VSCode中的Haskell扩展仍无法正确自动完成.使用 stack 方法会给出警告，例如 do-notation语句丢弃了类型为... 的结果，并且出现了诸如 Cannot推断出...之类的错误，这些错误是由使用引起的的... .实际上，第一个警告应该已经用 pandoc.cabal ghc-options 中的 -fno-warn-unused-do-bind 标志取消了>文件(假设这是扩展名读取的内容，以打印警告/错误).因此，我不知道是什么原因导致了这些错误.在构建过程中从Hackage下载回购库时，它们不存在.关于这个问题，我可能需要在堆栈溢出问题上再问一个问题.

However one part of my problem remains. When following both approaches the Haskell extension in VSCode still does not properly autocomplete. Using the stack approach gives warnings like A do-notation statement discarded a result of type ... and errors like Could not deduce ... arising from a use of .... The first warning should actually already be suppressed with the -fno-warn-unused-do-bind flag in ghc-options within the pandoc.cabal file (assuming this is what the extension reads in order to print warnings/errors). So I don't know what is responsible for these errors. They are not present when the repo was downloaded from Hackage during the build process. I will probably need to ask another question on stack overflow regarding this issue.

无论如何，由于标题中的问题得到了回答，我希望这会在将来的某个时候对某人有所帮助.

Anyway since the question in headline is answered, I hope this helps someone at some point in the future.

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