Could not find module

[dehlong]

Your environment

Which OS do you use: ArchLinux

Steps to reproduce

1. Create a basic Cabal Project
2. Make more files in the same directory as Main.hs
3. Import one of the other files (also add it to .cabal file.
4. VsCode complains that Could not find module ‘InfixHelpers’ even though they are there. I can run my project normally

Expected behaviour

Do not give red underline about not being able to find module when it is perfectly visible.

Actual behaviour

Gets underlined and error is displayed.

Include debug information

Execute in the root of your project the command haskell-language-server-wrapper --debug . and paste the logs here (you can find the executable location here):

Debug output:

No 'hie.yaml' found. Try to discover the project type!
Run entered for haskell-language-server-wrapper(haskell-language-server-wrapper) Version 2.13.0.0 x86_64 ghc-9.10.3
Current directory: /home/samo/Documents/Programming/FunctionalUniCoding/Precompression
Operating system: linux
Arguments: ["--debug"]
Cradle directory: /home/samo/Documents/Programming/FunctionalUniCoding/Precompression
Cradle type: Cabal

Tool versions found on the $PATH
cabal:          3.16.1.0
stack:          3.7.1
ghc:            9.6.7


Consulting the cradle to get project GHC version...
2026-04-11T15:55:22.613658Z | Debug | cabal --numeric-version
2026-04-11T15:55:22.695104Z | Debug | cabal path --output-format=json
2026-04-11T15:55:22.768185Z | Debug | /home/samo/.ghcup/bin/ghc --numeric-version
Project GHC version: 9.6.7
haskell-language-server exe candidates: ["haskell-language-server-9.6.7","haskell-language-server"]
Launching haskell-language-server exe at:/home/samo/.ghcup/bin/haskell-language-server-9.6.7
2026-04-11T15:55:22.860423Z | Debug | cabal path --output-format=json
2026-04-11T15:55:23.065037Z | Debug | /home/samo/.ghcup/bin/ghc -v0 -package-env=- -ignore-dot-ghci -e Control.Monad.join (Control.Monad.fmap System.IO.putStr System.Environment.getExecutablePath)
2026-04-11T15:55:23.157911Z | Debug | cabal path --output-format=json
2026-04-11T15:55:23.233905Z | Debug | /home/samo/.ghcup/bin/ghc --print-libdir
2026-04-11T15:55:24.987101Z | Info | haskell-language-server version: 2.13.0.0 (GHC: 9.6.7) (PATH: /home/samo/.ghcup/hls/2.13.0.0/lib/haskell-language-server-2.13.0.0/bin/haskell-language-server-9.6.7)
2026-04-11T15:55:24.988619Z | Info | Directory: /home/samo/Documents/Programming/FunctionalUniCoding/Precompression
2026-04-11T15:55:24.989236Z | Info | Logging heap statistics every 60.00s
 ghcide setup tester in /home/samo/Documents/Programming/FunctionalUniCoding/Precompression.
Report bugs at https://github.com/haskell/haskell-language-server/issues

Step 1/4: Finding files to test in /home/samo/Documents/Programming/FunctionalUniCoding/Precompression
2026-04-11T15:55:25.015278Z | Info | Using git to list file, relying on .gitignore
Found 5 files

Step 2/4: Looking for hie.yaml files that control setup
Found 1 cradle
  ()

Step 3/4: Initializing the IDE
2026-04-11T15:55:25.026848Z | Debug | Initializing exports map from hiedb
2026-04-11T15:55:25.027749Z | Debug | Shake session initialized

Step2026-04-11T15:55:25.028988Z | Debug | Done initializing exports map from hiedb. Size: 11
 4/4: Type checking the files
2026-04-11T15:55:25.030911Z | Info | Cradle path: app/VdzHelpers.hs
2026-04-11T15:55:25.031055Z | Warning | No [cradle](https://github.com/mpickering/hie-bios#hie-bios) found for app/VdzHelpers.hs.
Proceeding with [implicit cradle](https://hackage.haskell.org/package/implicit-hie).
You should ignore this message, unless you see a 'Multi Cradle: No prefixes matched' error.
2026-04-11T15:55:25.032974Z | Debug | Cradle: Cradle{ cradleRootDir = "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression", cradleOptsProg = CradleAction: Cabal}
2026-04-11T15:55:25.033043Z | Info | invoking build tool to determine build flags (this may take some time depending on the cache)
2026-04-11T15:55:25.033112Z | Debug | Requested to load Cabal cradle using single file mode
2026-04-11T15:55:25.054896Z | Debug | cabal --numeric-version
2026-04-11T15:55:25.137124Z | Debug | cabal path --output-format=json
2026-04-11T15:55:25.204544Z | Debug | /home/samo/.ghcup/bin/ghc --numeric-version
2026-04-11T15:55:25.204841Z | Info | Load cabal cradle using single file
2026-04-11T15:55:25.204966Z | Debug | Cabal Loading file /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/VdzHelpers.hs
    from project:  [ /home/samo/Documents/Programming/FunctionalUniCoding/Precompression ]
    with prefixes: 
    with actual loading files: [ /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/VdzHelpers.hs ]
2026-04-11T15:55:25.206462Z | Info | cabal v2-repl --keep-temp-files --with-repl /home/samo/.cache/hie-bios/repl-wrapper-fae20739a232ed1b9dcdf40eca9cf71e /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/VdzHelpers.hs
  Environment Variables
    HIE_BIOS_OUTPUT: /tmp/HIE_BIOS_OUTPUT47831-0
2026-04-11T15:55:26.386200Z | Debug | Resolving dependencies...
2026-04-11T15:55:26.655745Z | Debug | Build profile: -w ghc-9.6.7 -O1
2026-04-11T15:55:26.655920Z | Debug | In order, the following will be built (use -v for more details):
2026-04-11T15:55:26.656020Z | Debug |  - Precompression-0.1.0.0 (interactive) (exe:Precompression) (configuration changed)
2026-04-11T15:55:26.670083Z | Debug | Configuring executable 'Precompression' for Precompression-0.1.0.0...
2026-04-11T15:55:27.463010Z | Debug | Preprocessing executable 'Precompression' for Precompression-0.1.0.0...
2026-04-11T15:55:27.576552Z | Debug | cabal path --output-format=json
2026-04-11T15:55:27.624893Z | Debug | /home/samo/.ghcup/bin/ghc --print-libdir
2026-04-11T15:55:27.686514Z | Debug | cabal path --output-format=json
2026-04-11T15:55:27.733677Z | Debug | /home/samo/.ghcup/bin/ghc --numeric-version
2026-04-11T15:55:27.733905Z | Debug | Session loading result: Right (ComponentOptions {componentOptions = ["-package-env=-","-fbuilding-cabal-package","-O0","-outputdir","dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/Precompression-tmp","-odir","dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/Precompression-tmp","-hidir","dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/Precompression-tmp","-hiedir","dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/Precompression-tmp/extra-compilation-artifacts/hie","-stubdir","dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/Precompression-tmp","-i","-iapp","-idist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/Precompression-tmp","-idist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen","-idist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/global-autogen","-Idist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen","-Idist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/global-autogen","-Idist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/Precompression-tmp","-optP-include","-optPdist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/cabal_macros.h","-this-unit-id","Precompression-0.1.0.0-inplace-Precompression","-hide-all-packages","-Wmissing-home-modules","-no-user-package-db","-package-db","/home/samo/.local/state/cabal/store/ghc-9.6.7/package.db","-package-db","/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/packagedb/ghc-9.6.7","-package-db","dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/package.conf.inplace","-package-id","base-4.18.3.0","-XHaskell2010","app/Main.hs","InfixHelpers","VdzHelpers","-Wall","-hide-all-packages"], componentRoot = "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression", componentDependencies = ["Precompression.cabal","cabal.project","cabal.project.local"]},"/home/samo/.ghcup/ghc/9.6.7/lib/ghc-9.6.7/lib","9.6.7")
2026-04-11T15:55:27.749201Z | Info | Interface files cache directory: /home/samo/.cache/ghcide/Precompression-0.1.0.0-inplace-Precompression-41fd48fa3f5d15ef311363cb89a81cf512f1c1fc
2026-04-11T15:55:27.758191Z | Info | Making new HscEnv. In-place unit ids: [ Precompression-0.1.0.0-inplace-Precompression ]
2026-04-11T15:55:27.791052Z | Debug | New component cache HscEnvEq: (([],Just HscEnvEq 4),fromList [("/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/Precompression.cabal",Just 2026-04-10 12:29:46.614033638 UTC),("/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/cabal.project",Nothing),("/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/cabal.project.local",Nothing)])
2026-04-11T15:55:27.795741Z | Debug | Finished build session
AsyncCancelled
2026-04-11T15:55:27.796628Z | Debug | Known files updated:
  fromList [(TargetFile NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/VdzHelpers.hs",fromList ["/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/VdzHelpers.hs"]),(TargetModule (ModuleName "VdzHelpers"),fromList ["/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/VdzHelpers.hs"]),(TargetFile NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/Main.hs",fromList ["/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/Main.hs"]),(TargetModule (ModuleName "InfixHelpers"),fromList ["/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/InfixHelpers.hs"])]
2026-04-11T15:55:27.796783Z | Debug | Restarting build session due to new component
Action Queue: [User TypeCheck]
Keys: [GhcSessionIO; , GetKnownTargets; ]
Aborting previous build session took 0.00s 
2026-04-11T15:55:27.797566Z | Debug | hlint: Getting hlint ideas for  NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs"
2026-04-11T15:55:27.797689Z | Debug | hlint: Getting hlint ideas for  NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs"
2026-04-11T15:55:27.797969Z | Debug | hlint: Getting hlint ideas for  NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/VdzHelpers.hs"
2026-04-11T15:55:27.798221Z | Debug | hlint: Getting hlint ideas for  NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/InfixHelpers.hs"
2026-04-11T15:55:27.798340Z | Debug | hlint: Getting hlint ideas for  NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/Main.hs"
2026-04-11T15:55:27.954836Z | Info | Cradle path: dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs
2026-04-11T15:55:27.954966Z | Warning | No [cradle](https://github.com/mpickering/hie-bios#hie-bios) found for dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs.
Proceeding with [implicit cradle](https://hackage.haskell.org/package/implicit-hie).
You should ignore this message, unless you see a 'Multi Cradle: No prefixes matched' error.
2026-04-11T15:55:27.955928Z | Debug | Cradle: Cradle{ cradleRootDir = "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression", cradleOptsProg = CradleAction: Cabal}
2026-04-11T15:55:27.955967Z | Info | invoking build tool to determine build flags (this may take some time depending on the cache)
2026-04-11T15:55:27.956003Z | Debug | Requested to load Cabal cradle using single file mode
2026-04-11T15:55:28.034976Z | Debug | cabal --numeric-version
2026-04-11T15:55:28.133105Z | Debug | cabal path --output-format=json
2026-04-11T15:55:28.181716Z | Debug | /home/samo/.ghcup/bin/ghc --numeric-version
2026-04-11T15:55:28.181915Z | Info | Load cabal cradle using single file
2026-04-11T15:55:28.182006Z | Debug | Cabal Loading file /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs
    from project:  [ /home/samo/Documents/Programming/FunctionalUniCoding/Precompression ]
    with prefixes: 
    with actual loading files: [ /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs ]
2026-04-11T15:55:28.183050Z | Info | cabal v2-repl --keep-temp-files --with-repl /home/samo/.cache/hie-bios/repl-wrapper-fae20739a232ed1b9dcdf40eca9cf71e /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs
  Environment Variables
    HIE_BIOS_OUTPUT: /tmp/HIE_BIOS_OUTPUT47831-1
2026-04-11T15:55:28.209590Z | Debug | Error: [Cabal-7121]
2026-04-11T15:55:28.209781Z | Debug | Failed extracting script block: `{- cabal:` start marker not found
2026-04-11T15:55:28.209864Z | Debug | 
2026-04-11T15:55:28.219831Z | Debug | Session loading result: Left [CradleError {cradleErrorDependencies = ["Precompression.cabal","cabal.project","cabal.project.local"], cradleErrorExitCode = ExitFailure 1, cradleErrorStderr = ["Failed to run cabal v2-repl --keep-temp-files --with-repl /home/samo/.cache/hie-bios/repl-wrapper-fae20739a232ed1b9dcdf40eca9cf71e /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs in directory \"/home/samo/Documents/Programming/FunctionalUniCoding/Precompression\". Consult the logs for full command and error.","Failed command: cabal v2-repl --keep-temp-files --with-repl /home/samo/.cache/hie-bios/repl-wrapper-fae20739a232ed1b9dcdf40eca9cf71e /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs","","Error: [Cabal-7121]\nFailed extracting script block: `{- cabal:` start marker not found\n\n","","Process Environment:"], cradleErrorLoadingFiles = ["/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs"]}]
2026-04-11T15:55:28.221525Z | Info | Cradle path: dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs
2026-04-11T15:55:28.222443Z | Warning | No [cradle](https://github.com/mpickering/hie-bios#hie-bios) found for dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs.
Proceeding with [implicit cradle](https://hackage.haskell.org/package/implicit-hie).
You should ignore this message, unless you see a 'Multi Cradle: No prefixes matched' error.
2026-04-11T15:55:28.224819Z | Debug | Cradle: Cradle{ cradleRootDir = "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression", cradleOptsProg = CradleAction: Cabal}
2026-04-11T15:55:28.224930Z | Info | invoking build tool to determine build flags (this may take some time depending on the cache)
2026-04-11T15:55:28.225007Z | Debug | Requested to load Cabal cradle using single file mode
2026-04-11T15:55:28.250199Z | Debug | cabal --numeric-version
2026-04-11T15:55:28.307928Z | Debug | cabal path --output-format=json
2026-04-11T15:55:28.361039Z | Debug | /home/samo/.ghcup/bin/ghc --numeric-version
2026-04-11T15:55:28.361245Z | Info | Load cabal cradle using single file
2026-04-11T15:55:28.361326Z | Debug | Cabal Loading file /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs
    from project:  [ /home/samo/Documents/Programming/FunctionalUniCoding/Precompression ]
    with prefixes: 
    with actual loading files: [ /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs ]
2026-04-11T15:55:28.362102Z | Info | cabal v2-repl --keep-temp-files --with-repl /home/samo/.cache/hie-bios/repl-wrapper-fae20739a232ed1b9dcdf40eca9cf71e /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs
  Environment Variables
    HIE_BIOS_OUTPUT: /tmp/HIE_BIOS_OUTPUT47831-2
2026-04-11T15:55:28.389243Z | Debug | Error: [Cabal-7121]
2026-04-11T15:55:28.389355Z | Debug | Failed extracting script block: `{- cabal:` start marker not found
2026-04-11T15:55:28.389393Z | Debug | 
2026-04-11T15:55:28.399336Z | Debug | Session loading result: Left [CradleError {cradleErrorDependencies = ["Precompression.cabal","cabal.project","cabal.project.local"], cradleErrorExitCode = ExitFailure 1, cradleErrorStderr = ["Failed to run cabal v2-repl --keep-temp-files --with-repl /home/samo/.cache/hie-bios/repl-wrapper-fae20739a232ed1b9dcdf40eca9cf71e /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs in directory \"/home/samo/Documents/Programming/FunctionalUniCoding/Precompression\". Consult the logs for full command and error.","Failed command: cabal v2-repl --keep-temp-files --with-repl /home/samo/.cache/hie-bios/repl-wrapper-fae20739a232ed1b9dcdf40eca9cf71e /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs","","Error: [Cabal-7121]\nFailed extracting script block: `{- cabal:` start marker not found\n\n","","Process Environment:"], cradleErrorLoadingFiles = ["/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs"]}]
2026-04-11T15:55:28.400953Z | Info | updateFileDiagnostics published different from new diagnostics - file diagnostics: File:    
  /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs
Hidden:   no
Range:    1:1-2:1
Source:   cradle
Severity: DiagnosticSeverity_Error
Code:     <none>
Message: 
  Loading the module
  '/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs'
  failed.

  It may not be listed in your .cabal file!
  Perhaps you need to add `Paths_Precompression` to other-modules or exposed-modules.

  For more information, visit:
  https://cabal.readthedocs.io/en/3.4/developing-packages.html#modules-included-in-the-package
2026-04-11T15:55:28.401493Z | Info | updateFileDiagnostics published different from new diagnostics - file diagnostics: File:    
  /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs
Hidden:   no
Range:    1:1-2:1
Source:   cradle
Severity: DiagnosticSeverity_Error
Code:     <none>
Message: 
  Loading the module
  '/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs'
  failed.

  It may not be listed in your .cabal file!
  Perhaps you need to add `PackageInfo_Precompression` to other-modules or exposed-modules.

  For more information, visit:
  https://cabal.readthedocs.io/en/3.4/developing-packages.html#modules-included-in-the-package
2026-04-11T15:55:28.407239Z | Debug | hlint: Using extensions for  NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/VdzHelpers.hs":
    [ MonomorphismRestriction
    , DeepSubsumption
    , RelaxedPolyRec
    , ForeignFunctionInterface
    , ImplicitPrelude
    , DoAndIfThenElse
    , EmptyDataDecls
    , PatternGuards
    , DatatypeContexts
    , TraditionalRecordSyntax
    , StarIsType
    , CUSKs
    , FieldSelectors ]
2026-04-11T15:55:28.479811Z | Debug | hlint: Using extensions for  NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/InfixHelpers.hs":
    [ MonomorphismRestriction
    , DeepSubsumption
    , RelaxedPolyRec
    , ForeignFunctionInterface
    , ImplicitPrelude
    , DoAndIfThenElse
    , EmptyDataDecls
    , PatternGuards
    , DatatypeContexts
    , TraditionalRecordSyntax
    , StarIsType
    , CUSKs
    , FieldSelectors ]
2026-04-11T15:55:28.480132Z | Debug | hlint: Using extensions for  NormalizedFilePath "/home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/Main.hs":
    [ MonomorphismRestriction
    , DeepSubsumption
    , RelaxedPolyRec
    , ForeignFunctionInterface
    , ImplicitPrelude
    , DoAndIfThenElse
    , EmptyDataDecls
    , PatternGuards
    , DatatypeContexts
    , TraditionalRecordSyntax
    , StarIsType
    , CUSKs
    , FieldSelectors ]
2026-04-11T15:55:28.480318Z | Info | hlint: updateFileDiagnostics published different from new diagnostics - file diagnostics: File:     /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/app/VdzHelpers.hs
Hidden:   no
Range:    10:5-10:32
Source:   hlint
Severity: DiagnosticSeverity_Information
Code:     refact:Use isNothing
Message:  Use isNothingFound:findLast2 x left == NothingWhy not:isNothing (findLast2 x left)
2026-04-11T15:55:28.586536Z | Debug | Finished: User TypeCheck Took: 0.76s
2026-04-11T15:55:28.616845Z | Debug | Finished: GetHie Took: 0.03s
F2026-04-11T15:55:28.617230Z | Debug | Finished: GenerateCore Took: 0.00s
iles that failed:
 * /home/2026-04-11T15:55:28.617396Z | Debug | LOOKUP PERSISTENT FOR: GetModSummaryWithoutTimestamps
samo/2026-04-11T15:55:28.618366Z | Debug | LOOKUP PERSISTENT FOR: GetModSummaryWithoutTimestamps
Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/PackageInfo_Precompression.hs
 * /home/samo/Documents/Programming/FunctionalUniCoding/Precompression/dist-newstyle/build/x86_64-linux/ghc-9.6.7/Precompression-0.1.0.0/x/Precompression/build/Precompression/autogen/Paths_Precompression.hs

Completed (3 files worked, 2 files failed)
2026-04-11T15:55:28.619370Z | Debug | LOOKUP PERSISTENT FOR: GhcSessionDeps
2026-04-11T15:55:28.619600Z | Debug | LOOKUP PERSISTENT FOR: GhcSessionDeps

[fendor]

Hi, thank you for your bug report!

Can you share your .cabal file and perhaps your directory structure? E.g., the output of tree without dist-newstyle?

[vidit-od]

hello @dehlong,

i have also faced a similar issue recently. If you are on VSCode this happens if your open window is not the root directory.

i.e in my case my folder structure was :

Folder1 
-> Folder2 
-> -> .cabal file 
-> -> other files 

in this case if i open my vscode at Folder 1 it will show the above error that you mentioned.
if i open folder2 in VS code the errors disappear.

Can you please confirm if this is the issue ? In case your VSCode was already open on root, we can investigate further.

Thanks;

[dehlong]

Hello,
here is the whole tree:

Precompression
├── app
│   ├── InfixHelpers.hs
│   ├── Main.hs
│   ╰── VdzHelpers.hs
├── dist-newstyle
│   ├── build
│     Not putting build files here
│   ├── packagedb
│   │   ╰── ghc-9.6.7
│   │       ├── package.cache
│   │       ╰── package.cache.lock
│   ╰── tmp
├── CHANGELOG.md
├── Precompression.cabal
╰── hie.yaml

And here is the the .cabal file:

cabal-version: 3.8
name: Precompression
version: 0.1.0.0
license: NONE
author: Samo Kosík
maintainer: samokosik@samokosik.com
build-type: Simple
extra-doc-files: CHANGELOG.md

common warnings
  ghc-options: -Wall

executable Precompression
  import: warnings
  main-is: Main.hs
  other-modules:
    InfixHelpers
    VdzHelpers

  build-depends: base ^>=4.18.3.0
  hs-source-dirs: app
  default-language: Haskell2010

[dehlong]

When I open the directory containing the root of my project, the issue disappears. However, when I open a directory one level above, it appears again. Adding hie.yaml fixes this no matter how I open the project. I do not know whether this is the intended behaviour. My hie.yaml is below:

cradle:
  cabal:
    - path: "app/Main.hs"
      component: "exe:Precompression"
    - path: "app/InfixHelpers.hs"
      component: "exe:Precompression"
    - path: "app/VdzHelpers.hs"
      component: "exe:Precompression"

[fendor]

However, when I open a directory one level above, it appears again

HLS fails to find the project root. I am not 100 % why this happens.
IIRC, having a cabal.project file should also work.

Example cabal.project:

packages: .

My hie.yaml is below:

This hie.yaml should be always usable and does what you want it to do:

cradle:
  cabal:

It essentially mainly marks the root of your project.