Haskell - 小烦恼

vscode-haskell

Toolchain 选择

在 .vscode/settings.json 中使用 haskell.toolchain 选择指定版本。

例

{
    "haskell.toolchain": {
        "hls": "2.2.0.0",
        "cabal": "3.10.1.0",
        "stack": "2.11.1"
    }
}

formatter 选择

floskell, ^config

LSP - Language Server Protocol

• Client: vscode-haskell ( vscode-languageclient )
• Server: haskell-language-server ( lsp, hls-graph, ghcide, hls-plugin, hie-bios, hiedb , GHC, ... )

遇到问题，不妨重启试试。

• hie-bios 目前优先设定为隐式发现。
• Multi Cradle: No prefixes matched, 先不关注
• Loading the module 'foo.hs' failed, 听从提示
• !!MISSING: command!!, 等等看

GHCi

Multi line

GHCi 里使用 :{ ... :}或使用 :set +m.

Loading a multi-module program

在 .hs 所在目录，GHCi 里使用 :load Main，会根据 impdecls 查找 import 项。

GHC Package environments

A package environment file is a file that tells ghc precisely which packages should be visible. 

控制某包是否可见，如某包不可见，GHC/GHCi 处理时会显示类似于It is a member of the hidden package 'base-4.17.2.0', 需要设置为可见。

-hide-all-packages, This is a good way to insulate your program from differences in the globally exposed packages, and being explicit about package dependencies is a Good Thing.

Cabal always passes the -hide-all-packages flag to GHC, for exactly this reason.

GHC/GHCi 会默认加载当前目录（及父目录）下的 package environment file, 其次全局；选项-package-env <file>指定加载.

Cabal ( cabal-install )

proj.cabal

先关注 other-modules 和 build-depends 项，其他项有更多需求再关注。

other-modules

For an executable, other modules included in the executable should be listed in the other-modules field.

build-depends

Instead, you add the package you want to use to the build-depends section of the .cabal file of your package.

Cabal will take care of fetching and building the dependency as needed when you run cabal build, cabal run, or other similar commands.

Cabal 项目中，在 build-depends添加依赖库名称，Cabal 会处理的。

Adding libraries to GHC package environments

cabal install --lib, 默认为全局,%APPDATA%/ghc/$ARCH-$OS-$GHCVER/environments/default.

cabal install --package-env 配合使用，确定使用哪个. 

更多

• 2022 State of Haskell Survey Results - <https://taylor.fausak.me/2022/11/18/haskell-survey-results/>
• 「Haskell に IDE はないのか？──独断と偏見による Haskell の IDE 十年史」 - <https://zenn.dev/konn/articles/1a60baba9848a1>
• Mitchell, N., Kiefer, M., Iborra, P., Lau, L., Duggal, Z., Siebenhandl, H., Sanchez, J. N., Pickering, M., & Zimmerman, A. Building an Integrated Development Environment (IDE) on top of a Build System: The tale of a Haskell IDE. Proceedings of the 32nd Symposium on Implementation and Application of Functional Languages, 1–10. 2020. https://doi.org/10.1145/3462172.3462180

 

• https://cabal.readthedocs.io/en/3.10/developing-packages.html#modules-included-in-the-package
• https://downloads.haskell.org/ghc/latest/docs/users_guide/packages.html#package-environments
• https://cabal.readthedocs.io/en/3.10/cabal-commands.html#cabal-install
• Separate cabal install --lib into own command (cabal env)  - <https://github.com/haskell/cabal/issues/6481>

 

• Improve the error message for unknown modules - <https://github.com/haskell/haskell-language-server/issues/3695>
• 2021 How to get VSCode to recognize a dependency - <https://github.com/tomjaguarpaw/tilapia/issues/93>
• HLS 2.3.0.0 release possibly borked on Windows - <https://github.com/haskell/haskell-language-server/issues/3822>