-p vs -E

output.txt

sundials@sundials:~/chebApprox$ nix-shell -E 'with import <nixpkgs> { config.allowUnfree = true; config.allowBroken = true; }; haskellPackages.ghcWithPackages (pkgs: [pkgs.accelerate])'

[nix-shell:~/chebApprox]$ ghci
GHCi, version 8.6.5: http://www.haskell.org/ghc/  :? for help
Prelude> import Data.Array.Accelerate

<no location info>: error:
    Could not find module ‘Data.Array.Accelerate’
    It is not a module in the current program, or in any known package.
Prelude> :q
Leaving GHCi.

[nix-shell:~/chebApprox]$ exit
sundials@sundials:~/chebApprox$ nix-shell -p "haskellPackages.ghcWithPackages (pkgs: [pkgs.accelerate])"

[nix-shell:~/chebApprox]$ ghci
GHCi, version 8.6.5: http://www.haskell.org/ghc/  :? for help
Prelude> import Data.Array.Accelerate
Prelude Data.Array.Accelerate>