`cabal repl` ignores `.ghci` files

[Soupstraw]

Describe the bug
cabal repl ignores the .ghci file in the project directory. I also tried to put the .ghci file into my home directory, passing a .ghci file via the -ghci-script option, but the file is never loaded no matter which method I use.

To Reproduce
Steps to reproduce the behavior:

• Clone this project: https://github.com/input-output-hk/cardano-ledger
• Create a .ghci in the project directory with some content (for example :set prompt .ghci loaded)
• Run cabal v2-repl test:cardano-ledger-alonzo-test --ghc-options="-Wwarn"

After doing the steps above, the .ghci file is ignored by the REPL and it runs as it would without a .ghci file.

Expected behavior
The repl starts and runs all the commands in the .ghci file.

System information

• NixOS
• cabal 3.8.1.0
• ghc 8.10.7

[Mikolaj]

Thank you for the report. Does it ever work? I suppose ghci works fine? Does cabal repl do what it should in any circumstance? In older versions of cabal? With special options? Not under Nix? On Windows? With newer GHC?

[sorki]

I've tested (different repository which doesn't use haskell.nix) with

• NixOS
• cabal 3.10.1.0
• ghc 9.4.6

and it works, both ./.ghci and ~/.ghc/ghci.conf are loaded. I think this can be safely closed.

[goertzenator]

I can add some insight here:

For multi-package projects, cabal repl will indeed ignore the project .ghci file when run at the project level. My work around was to push the .ghci file into the package directory I was working with, and then it worked.

I expect cabal repl to check the current directory for a .ghci because that's what the documentation says. This is a valid bug that should be reopened.

[geekosaur]

If I run bare ghci from a project directory, it's also not read. Which makes it ghc's bug that we can't do anything about.

[hasufell]

If I run bare ghci from a project directory, it's also not read. Which makes it ghc's bug that we can't do anything about.

I cannot confirm this.

---

My use case is that I want to run cabal repl -b foo,bar,baz in an empty directory with just a .ghci file to do some exercises from a book I'm reading. I don't need a project or package. The .ghci file is ignored. ghci does correctly read it.

There are workarounds, but it's bad UX.

[ozkutuk]

For multi-package projects, cabal repl will indeed ignore the project .ghci file when run at the project level.

I have found this workaround for multi-package projects:

cabal repl <package> --repl-options="-ghci-script=$PWD/.ghci"

[ozkutuk]

I did some digging around, and found out the following:

With cabal repl <package>, the current working directory is set as the package root, rather than the project root. This can be confirmed by running :show paths inside the REPL:

$ tree
.
├── package-a
│   ├── package-a.cabal
│   └── ...
├── package-b
│   ├── package-b.cabal
│   └── ...
└── cabal.project

$ cabal repl package-a
...
ghci> :show paths
current working directory:
  /home/ozkutuk/dev/cabal-multi-repro/package-a
module import search paths:
  src
  /home/ozkutuk/dev/cabal-multi-repro/dist-newstyle/build/x86_64-linux/ghc-9.6.6/package-a-0.1.0.0/build
  /home/ozkutuk/dev/cabal-multi-repro/dist-newstyle/build/x86_64-linux/ghc-9.6.6/package-a-0.1.0.0/build/autogen
  /home/ozkutuk/dev/cabal-multi-repro/dist-newstyle/build/x86_64-linux/ghc-9.6.6/package-a-0.1.0.0/build/global-autogen

Therefore, .ghci is not picked up since it's only searched within the current working directory. Now, this is not an issue with multi-repl support, which can once again be checked by :show paths:

$ cabal repl all --enable-multi-repl
ghci> :show paths
current working directory:
  /home/ozkutuk/dev/cabal-multi-repro
module import search paths:
  src
  /home/ozkutuk/dev/cabal-multi-repro/dist-newstyle/build/x86_64-linux/ghc-9.6.6/package-a-0.1.0.0/build
  /home/ozkutuk/dev/cabal-multi-repro/dist-newstyle/build/x86_64-linux/ghc-9.6.6/package-a-0.1.0.0/build/autogen
  /home/ozkutuk/dev/cabal-multi-repro/dist-newstyle/build/x86_64-linux/ghc-9.6.6/package-a-0.1.0.0/build/global-autogen

And GHCi reports that it has loaded .ghci:

Loaded GHCi configuration from /home/ozkutuk/dev/cabal-multi-repro/.ghci

Multi-repl does not yet support every command, but for my use case it was enough (i.e. setting a few language pragmas and overriding interactive-print through :seti).

(cc: @goertzenator)