使用Stack安装elm-export后构建失败的问题求助

Hey there! Let's work through this issue together. You ran stack install elm-export without errors, but stack build is still failing—here are the most likely causes and how to fix them:

1. elm-export isn't listed in your project's dependencies #

Running stack install only installs the package to your global Stack environment, but your project doesn't know to use it unless you explicitly add it to your dependency list. Stack strictly uses the dependencies defined in your package.yaml or .cabal file when building your project.

• Fix steps:
  • Open your project's package.yaml (preferred) and add elm-export to the dependencies section. If you need a specific version to match servant-elm, specify it like this:

    dependencies:
      - base >= 4.7 && < 5
      - servant-elm
      - elm-export >= 0.12.0 && < 0.13
    

  • If you're using a .cabal file instead, add elm-export to the build-depends field of your executable/library stanza:

    executable test
      build-depends:
          base >=4.7 && <5
        , servant-elm
        , elm-export >=0.12.0
    

  • Run stack build again—Stack will now fetch and use the correct version of elm-export for your project.

2. Version mismatch between elm-export and servant-elm #

It's possible the global version of elm-export you installed doesn't play nice with the version of servant-elm in your project. Servant-elm has strict compatibility requirements with elm-export, so a version mismatch can break builds.

• Fix steps:
  • Check the servant-elm package's compatibility notes (you can run stack info servant-elm to see details) to confirm which elm-export versions it supports.
  • Pin the correct elm-export version in your package.yaml or .cabal file as shown above.
  • Run stack build—Stack will resolve the compatible version and build correctly.

3. Corrupted build cache #

Sometimes Stack's local build cache can get into a weird state, even if the package was installed globally. Old cached artifacts might be interfering with the build.

• Fix steps:
  • Run stack clean to wipe the local build cache.
  • Run stack build again—this will force Stack to recompile everything from scratch, using the dependencies you've specified.

4. Incomplete error message #

The error snippet you shared gets cut off right when the actual compile error would be shown. The full message (like a missing module, type mismatch, or import error) is critical to pinpointing the exact issue.

• Fix steps:
  • Re-run stack build and copy the entire error output, including the final lines that explain what went wrong. Sharing that full message will let us give you a more targeted fix.

内容的提问来源于stack exchange，提问作者Johnny Liao