pinning.pkgs

let servantOverlay = self: super: {                                                                                                            │
      haskellPackages = super.haskellPackages.override {                                                                                       │[nix-shell:~/work/dbpoc]$ ghc-pkg list | grep serva^C                                       
        overrides = hself: hsuper:                                                                                                             │
          {                                                                                                                                    │[nix-shell:~/work/dbpoc]$ exit
            servant = hself.callHackage "servant" "0.16" {};                                                                                   │
            servant-client-core = hself.callHackage "servant-client-core" "0.16" {};                                                           │[rsoeldner@nixos:~/work/dbpoc]$ nix-shell --pure                                            
            servant-server = hself.callHackage "servant-server" "0.16" {};                                                                     │
            servant-client = hself.callHackage "servant-client" "0.16" {};                                                                     │[nix-shell:~/work/dbpoc]$ ghc-pkg list | grep webs                                          
            #servant-multipart = hself.callCabal2nix "servant-multipart" ./deps/servant-multipart {};                                          │    servant-websockets-1.2.0
            servant-websockets = hsuper.callCabal2nix "servant-websockets" ./deps/servant-websockets {};                                       │    wai-websockets-3.0.1.2
          };                                                                                                                                   │    websockets-0.12.5.3
        };                                                                                                                                     │
      };                                                                                                                                       │[nix-shell:~/work/dbpoc]$ exit
in import (builtins.fetchTarball                                                                                                               │
    {name = "N";                                                                                                                               │[rsoeldner@nixos:~/work/dbpoc]$ nix-shell
     url = "https://github.com/nixos/nixpkgs/archive/f52505fac8c82716872a616c501ad9eff188f97f.tar.gz";                                         │
     sha256 = "0q2m2qhyga9yq29yz90ywgjbn9hdahs7i8wwlq7b55rdbyiwa5dy";                                                                          │[nix-shell:~/work/dbpoc]$ ghc-pkg list | grep webs                                          
    }) { config = {}; overlays = [ servantOverlay ]; }                                                                                         │    websockets-0.12.5.3