let # import niv packages sources = import ./nix/sources.nix; overlay = _: pkgs: { niv = import sources.niv {}; # use the sources :) }; # Import the Haskell.nix library, #pkgs = import (import (builtins.fetchTarball https://github.com/input-output-hk/haskell.nix/archive/master.tar.gz)); pkgs = import sources.nixpkgs ( overlays = [ overlay ]; config = {}; import (builtins.fetchTarball https://github.com/input-output-hk/haskell.nix/archive/master.tar.gz) ); # Import the file you will create in the stack-to-nix or cabal-to-nix step. my-pkgs = import ./pkgs.nix; # Cabal projects use this: pkgSet = pkgs.haskell-nix.mkCabalProjectPkgSet { plan-pkgs = my-pkgs; pkg-def-extras = []; modules = [ # specific package overrides would go here # example: # packages.cbors.package.ghcOptions = "-Werror"; # packages.cbors.patches = [ ./one.patch ]; # packages.cbors.flags.optimize-gmp = false; # It may be better to set flags in `cabal.project` instead # (`plan-to-nix` will include them as defaults). ]; }; in pkgSet.config.hsPkgs // { _config = pkgSet.config; }