Pin nixpkgs.

Author: dmjio

default.nix

@@ -1,4 +1,8 @@
-{ pkgs ? import <nixpkgs> {}
+with (builtins.fromJSON (builtins.readFile ./nixpkgs.json));
+{ pkgs ? import (builtins.fetchTarball {
+    url = "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz";
+    inherit sha256;
+  }) {}
 , compiler ? "ghc881"
 }:
 let

nixpkgs.json

@@ -0,0 +1,3 @@
+{ "rev" : "cc1ae9f21b9"
+, "sha256" : "0zjafww05h50ncapw51b5qxgbv9prjyag0j22jnfc3kcs5xr4ap0"
+}