I encountered a bug in cardano-node recently and since I know Haskell - I thought to myself, why not try and fix it?

I've done the following:

  1. Build from source per https://github.com/input-output-hk/cardano-node/blob/master/doc/getting-started/install.md/
  2. Install ghcid through stack
  3. However, when running ghcid -c "cabal repl exe:cardano-node --reorder-goals" as per documentation results in the following error:
$ ghcid -c "cabal repl exe:cardano-node --reorder-goals"
Loading cabal repl exe:cardano-node --reorder-goals ...
Warning: Requested index-state 2021-04-30T00:00:00Z is newer than
'hackage.haskell.org'! Falling back to older state (2021-04-29T23:07:55Z).
Resolving dependencies...
Build profile: -w ghc-8.10.4 -O1
In order, the following will be built (use -v for more details):
 - cardano-node-1.27.0 (exe:cardano-node) (ephemeral targets)
Preprocessing executable 'cardano-node' for cardano-node-1.27.0..
GHCi, version 8.10.4: https://www.haskell.org/ghc/  :? for help
*** Exception: The following packages were specified via -package or -package-id flags,
but were not needed for compilation:
  - text-
  - optparse-applicative-
  - cardano-prelude-
  - cardano-node-1.27.0
  - cardano-config-

No files loaded, GHCi is not working properly.
Command: cabal repl exe:cardano-node --reorder-goals

Update: I guess for local development, I can probably work around this by setting

package cardano-node
  ghc-options: -Wwarn

in cabal.project, but that seems undesirable. It's been over 8 years since I've last used Haskell & Cabal, so I'm still figuring it all out again heh. But I guess something is slightly misconfigured?

Output when setting -Wwarn for cardano-node:

[1 of 2] Compiling Paths_cardano_node ( /home/weebl/git/cardano-node/dist-newstyle/build/x86_64-linux/ghc-8.10.4/cardano-node-1.27.0/x/cardano-node/build/cardano-node/autogen/Paths_cardano_node.hs, interpreted )
[2 of 2] Compiling Main             ( app/cardano-node.hs, interpreted )
Ok, two modules loaded.

All good (2 modules, at 04:45:39)

If anyone knows which steps I'm missing, please let me know.

GHC 8.10.4 Cabal ghcid v0.8.7 OS: Ubuntu 21.04 x86-64

Thanks in advance!

  • 2
    until somebody more knowledgeable in this matter chimes in; you could try running this in a nix-shell (NixOS)
    – Matthias Sieber
    Jun 1, 2021 at 2:19

1 Answer 1


Try to give the guild cntools build script a look


It probably contains all the information about the initial setup (try ghcup), the cabal.project file, submodules ecc

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