❯  nix shell --impure --expr "(import (builtins.getFlake \"nixpkgs\") {}).pkgsStatic.haskellPackages.shellFor { packages = (p: [ p.aeson p.typed-process p.bytestring p.lens p.lens-aeson]);}"
error:
       … while calling a functor (an attribute set with a '__functor' attribute)
         at /nix/store/s8b6phy15mzjvx56vjdd1rdd8hr07qw5-source/pkgs/development/haskell-modules/make-package-set.nix:613:29:
          612|       # pkgWithCombinedDeps :: HaskellDerivation
          613|       pkgWithCombinedDeps = self.mkDerivation (genericBuilderArgsModifier genericBuilderArgs);
             |                             ^
          614|

       … while evaluating a branch condition
         at /nix/store/s8b6phy15mzjvx56vjdd1rdd8hr07qw5-source/lib/customisation.nix:173:7:
          172|       in
          173|       if isAttrs result then
             |       ^
          174|         result

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: expected a set but found null: null

In reply to @woobilicious:matrix.org

❯  nix shell --impure --expr "(import (builtins.getFlake \"nixpkgs\") {}).pkgsStatic.haskellPackages.shellFor { packages = (p: [ p.aeson p.typed-process p.bytestring p.lens p.lens-aeson]);}"
error:
       … while calling a functor (an attribute set with a '__functor' attribute)
         at /nix/store/s8b6phy15mzjvx56vjdd1rdd8hr07qw5-source/pkgs/development/haskell-modules/make-package-set.nix:613:29:
          612|       # pkgWithCombinedDeps :: HaskellDerivation
          613|       pkgWithCombinedDeps = self.mkDerivation (genericBuilderArgsModifier genericBuilderArgs);
             |                             ^
          614|

       … while evaluating a branch condition
         at /nix/store/s8b6phy15mzjvx56vjdd1rdd8hr07qw5-source/lib/customisation.nix:173:7:
          172|       in
          173|       if isAttrs result then
             |       ^
          174|         result

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: expected a set but found null: null

1. I think you misunderstand the inputs for shellFor. The packages input should be the packages you're developing. shellFor won't install them, only their dependencies.
2. pkgsStatic usually requires cross-compilation. If you run into evaluation or build problems, this is probably why.
3. bytestring is a boot library preinstalled with GHC, so Nixpkgs sets it to null (this is why sterni has suggested you remove it).
4. For smaller outputs, consider also using justStaticExecutables.

λlice: Do you mean generating completion for optparse applicative parameters? There is a helper for that in nixpkgs, but I don’t know how to integrate it with haskell-flake.

There might be other venues, where there is more discussion about haskell-flake, the readme is e.g. linking a zulip, since the maintainer of haskell-flake is banned from nixos community rooms.

Hello, does anyone have experience with building haskell on macOS? This project compiles fine on linux where nix uses gcc by default. it fails on darwin however as the default compiler there is clang.

> /nix/store/q7lf35kha4z40zkmhf3cyipaf7kkk6if-cctools-binutils-darwin-wrapper-1010.6/bin/ld: line 268:  5770 Segmentation fault: 11  /nix/store/qib1l5hjzaycqyw9slc2j127wma1ayix-cctools-binutils-darwin-1010.6/bin/ld "@$responseFile"
       > clang-16: error: linker command failed with exit code 139 (use -v to see invocation)
       > ghc-9.6.6: `cc' failed in phase `Linker'. (Exit code: 1)

The system has a linux builder vm with nix-darwin enabled but I dont think its related to this error.