Haskell Language Server (HLS) issue #3074. https://github.com/haskell/haskell-language-server/issues/3074

.devcontainer.json

{
  "customizations": {
    "vscode": {
      "extensions": [
        "haskell.haskell"
      ]
    }
  },
  "dockerComposeFile": "compose.yaml",
  "service": "devcontainer",
  "workspaceFolder": "/workspaces/example"
}

cabal.project

packages:
  .
  flow-2.0.0.2.tar.gz

compose.yaml

{
  "services": {
    "devcontainer": {
      "command": "sh -c 'while sleep 1; do :; done'",
      "image": "public.ecr.aws/acilearning/haskell:9.4.4-be16c1942fc0c18391314839fdb1bd2e793c4287",
      "volumes": [
        ".:/workspaces/example"
      ],
      "working_dir": "/workspace/example"
    }
  }
}

example.cabal

cabal-version: >= 1.10
name: example
version: 0
build-type: Simple
library
  build-depends: base
  default-language: Haskell2010
  exposed-modules: Example

Example.hs

module Example where

flow-2.0.0.2.tar.gz

hie.yaml

{
  "cradle": {
    "cabal": null
  }
}