gistfile1.txt

➜  pandoc-online-editor git:(master) ✗ cat default.nix                                                     ~/Desktop/projects/nixcloud/pandoc-online-editor
with import <nixpkgs> { };

buildGoPackage rec {
  name = "nixcloud-${version}";
  version = "0.0.1";

  goPackagePath = "github.com/nixcloud/websocket";
  subPackages = [ "." ];

  buildInputs = [ pandoc ];
  goDeps = ./deps.json;
}

➜  pandoc-online-editor git:(master) ✗ cat deps.json                                                       ~/Desktop/projects/nixcloud/pandoc-online-editor
[
  {
    "include": "../../libs.json",
    "packages": [
      "golang.org/x/net",
      "golang.org/x/net/websocket"
    ]
  }
]%                                                                                                                                                          ➜  pandoc-online-editor git:(master) ✗ nix-shell --command "cd websocket-pandoc/src; go run main.go"       ~/Desktop/projects/nixcloud/pandoc-online-editor
chat/client.go:8:2: cannot find package "golang.org/x/net/websocket" in any of:
        /nix/store/0189nqxk2r4mb11fnd9g106ljzidg0h2-go-1.6.2/share/go/src/golang.org/x/net/websocket (from $GOROOT)
        /nix/store/fchfr2xqql0f2d9jiavr7fqvsnb5kk32-go1.6-govers-20150109-3b5f175/share/go/src/golang.org/x/net/websocket (from $GOPATH)
➜  pandoc-online-editor git:(master) ✗              

Does nix-build works for you here? I think that this could be related to nix-shell NixOS/nixpkgs#15490
I'll try to find some way to make it work