Don't run Haddock on packages that expose no modules about cabal2nix HOT 4 CLOSED

I don't understand why you consider this an issue with cabal2nix? The utility offers a --no-haddock command line switch you can use to generate a correct expression in such cases. Also, the transformers-compat package we have in Nixpkgs has the noHaddock=true bit set and installs just fine.

What exactly to you want us to do?

from cabal2nix.

For the vast majority of packages cabal2nix creates a nix expression and it installs perfectly. In this case it required a manual change inorder to install. I am not clear on why I needed to set the noHaddock flag in order for the installation to complete when no other package I have used cabal2nix on in the same system has needed it.

Ideally cabal2nix would be able to detect that noHaddock was needed in order install and add it appropriately. I can not tell weather this is possible or not because I not understand why transformers-compat needed and others did not, but from your response it sound like it is not possible. If it is not possible then the solution is additional documentation, which could be me adding a note to the haskell page on nixos.org/wiki or starting a page for cabal2nix and adding notes there. If it was important enough then it could going the README.md.

If I knew it was not possible to make the detection automatically then I would just add documentation to the wiki directly.

from cabal2nix.

transformers-compat fails the Haddock stage because it doesn't expose any modules to the user, so when Haddock is run, there are no input files for it. I guess, it would be possible to recognize this particular case in cabal2nix. I never thought much about it, though, because cases like transformers-compat (i.e. library package that don't expose any modules) are very rare. Auto-detecting this case simply didn't feel like a siginificant issue. The vast majority of packages that do require noHaddock=true are packages that have syntax errors in their Haddock documentation, and those cases we cannot autodetect.

Anyway, you are right saying that the documentation for cabal2nix should be improved to mention that issue.

from cabal2nix.

It's becoming increasingly common for authors to deprecate their package by releasing an empty version of the library that contains no visible modules, but a comment saying "this package is obsolete, use such-and-such instead". Builds of such packages invariably fail at first because we try to run haddock on them. Cabal2nix could recognize that a package has no contents and set noHaddock = true automatically.

from cabal2nix.