{ pkgs ? (import ./nix/nixpkgs) }:

let

compiler = "ghc8104";

source = pkgs.lib.sourceByRegex ./. [

"^.*\.md$"

"^capability\.cabal$"

"^examples.*$"

"^src.*$"

];

haskellPackages = pkgs.haskell.packages.${compiler}.override {

overrides = capabilityOverlay;

};

capabilityOverlay = self: super: {

"capability" = pkgs.haskell.lib.enableCabalFlag

(super.callCabal2nix "capability" source { }) "dev";

};

in {

capability = haskellPackages.capability;

shell = haskellPackages.shellFor {

packages = ps: [

ps.capability

];

buildInputs = [

haskellPackages.cabal-install

haskellPackages.ghcid

];

};

}