Haskell shell fails with recent nixpkgs

[jneem]

With a newly created organist environment, trying to use the HaskellStack shell fails with

error:
       … while calling the 'derivationStrict' builtin

         at /builtin/derivation.nix:9:12: (source not available)

       … while evaluating derivation 'shell'
         whose name attribute is located at «none»:0

       … while evaluating attribute 'nativeBuildInputs' of derivation 'shell'

         at «none»:0: (source not available)

       error: attribute 'hls-ormolu-plugin' missing

       at /nix/store/gziak2db5lgxszrxnkwpd8n8v98hcfm7-nickel-generated-expr:8:51:

            7|     hlsDependencies = getDependencies hls;
            8|     hlsOrmoluPluginDependencies = getDependencies hlsDependencies.hls-ormolu-plugin;

Maybe this is because hls-ormolu-plugin is broken?

Anyway, changing nixpkgs to nixpkgs/nixos-23.11 fixes it (but not 24.05; that's still broken).

[jneem]

Hm, unfortunately using a nixpkgs that's older than my system's nixpkgs doesn't work very well, possibly because of this. In my new organist shell, running stack new testpkg gives

error:
       … while calling the 'derivationStrict' builtin

         at /builtin/derivation.nix:9:12: (source not available)

       … while evaluating derivation 'myEnv'
         whose name attribute is located at /nix/store/fwdi5pvgkw12gr4mx7n35smj76dyy0k2-qk1dpz44db85rhd8lr4j6i2hkn9j5hg4-source/pkgs/stdenv/generic/make-derivation.nix:348:7

       … while evaluating attribute 'LD_LIBRARY_PATH' of derivation 'myEnv'

         at «string»:1:411:

            1| with (import <nixpkgs> {}); let inputs = [haskell.compiler.ghc965 git gcc gmp]; libPath = lib.makeLibraryPath inputs; stackExtraArgs = lib.concatMap (pkg: [ ''--extra-lib-dirs=${lib.getLib pkg}/lib''   ''--extra-include-dirs=${lib.getDev pkg}/include'' ]) inputs; in runCommand ''myEnv'' { buildInputs = lib.optional stdenv.isLinux glibcLocales ++ inputs; STACK_PLATFORM_VARIANT=''nix''; STACK_IN_NIX_SHELL=1; LD_LIBRARY_PATH = libPath;STACK_IN_NIX_EXTRA_ARGS = stackExtraArgs; LANG="en_US.UTF-8";} ""
             |                                                                                                                                                                                                                                                                                                                                                                                                                           ^

       error: attribute 'ghc965' missing

       at «string»:1:43:

            1| with (import <nixpkgs> {}); let inputs = [haskell.compiler.ghc965 git gcc gmp]; libPath = lib.makeLibraryPath inputs; stackExtraArgs = lib.concatMap (pkg: [ ''--extra-lib-dirs=${lib.getLib pkg}/lib''   ''--extra-include-dirs=${lib.getDev pkg}/include'' ]) inputs; in runCommand ''myEnv'' { buildInputs = lib.optional stdenv.isLinux glibcLocales ++ inputs; STACK_PLATFORM_VARIANT=''nix''; STACK_IN_NIX_SHELL=1; LD_LIBRARY_PATH = libPath;STACK_IN_NIX_EXTRA_ARGS = stackExtraArgs; LANG="en_US.UTF-8";} ""
             |                                           ^
       Did you mean one of ghc925, ghc945, ghc96, ghc962 or ghc963?

[thufschmitt]

Thanks for reporting that.

The HaskellStack shell is currently using some Nix trickery to get ormolu from the closure of hls (because ormolu-in-the-path and ormolu-in-the-lsp have to match to avoid inconsistencies in the formatting):

organist/lib/nix-interop/shells/haskell.ncl

Lines 7 to 27 in 879ca21

	# Haskell Language Server (HLS) uses a different Ormolu version than the default one, and it's difficult to change it for now.
	# See https://github.com/haskell/haskell-language-server/issues/411
	# So we do the opposite: retrieve the Ormolu package transitively pulled by HLS.
	# Note that Ormolu is a level 2 transitive dependency of HLS: `haskell-language-server` -> `hls-ormolu-plugin` -> `ormolu`
	ormoluFromHls = fun hls =>
	derivation.CallNix
	& {
	function = m%"
	hls:
	let
	# Build the attrset of dependency packages of `p`
	getDependencies = p: builtins.listToAttrs
	(map (dependency: { name = dependency.pname; value = dependency; }) p.passthru.getBuildInputs.haskellBuildInputs);
	hlsDependencies = getDependencies hls;
	hlsOrmoluPluginDependencies = getDependencies hlsDependencies.hls-ormolu-plugin;
	in
	hlsOrmoluPluginDependencies.ormolu.bin
	"%,
	args = hls,
	}

But the layout of the dependencies of hls changed between 23.11 and 24.05, breaking that.

I'm working on a fix to be compatible with both, will open a PR as soon as it's ready.

[simeoncarstens]

@jneem looks like this can be closed, right?

[jneem]

Yep, I just tested a new shell and it seems to work.