WIP: use niv for source management

nix/sources.json

@@ -0,0 +1,38 @@
+{
+    "niv": {
+        "branch": "master",
+        "description": "Easy dependency management for Nix projects",
+        "homepage": "https://github.com/nmattia/niv",
+        "owner": "nmattia",
+        "repo": "niv",
+        "rev": "5e9671a9a87c240b1c6ce981d04ad23ba4291451",
+        "sha256": "08j7msxkv452pyxnh0sgn6h9930i5mk9mszba49bj5401gzmfb8a",
+        "type": "tarball",
+        "url": "https://github.com/nmattia/niv/archive/5e9671a9a87c240b1c6ce981d04ad23ba4291451.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixpkgs": {
+        "branch": "nixos-19.03",
+        "description": "A read-only mirror of NixOS/nixpkgs tracking the released channels. Send issues and PRs to",
+        "homepage": "https://github.com/NixOS/nixpkgs",
+        "owner": "NixOS",
+        "repo": "nixpkgs-channels",
+        "rev": "7339bd47600f687dac692fea897bbf58c55631c4",
+        "sha256": "12nxr39pjhd8n0l91wsv1kvzdsa5zhhc5a0hndbi1zyxjdrlqsxa",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs-channels/archive/7339bd47600f687dac692fea897bbf58c55631c4.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixpkgs-master": {
+        "branch": "master",
+        "description": "Nix Packages collection",
+        "homepage": null,
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "92e653b19b613bba25cdd7367fe039697d70ecdf",
+        "sha256": "0aiq94nsyxwcal2f7kclb70fggzmw39gkz3l2cs384sv1kw4dmck",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs/archive/92e653b19b613bba25cdd7367fe039697d70ecdf.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    }
+}