Add a nix-shell

.envrc

@@ -0,0 +1 @@
+use nix

nix/nixpkgs-version.json

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+{
+  "url": "https://github.com/nixos/nixpkgs-channels.git",
+  "rev": "84d74ae9c9cbed73274b8e4e00be14688ffc93fe",
+  "date": "2020-09-26T18:54:09-07:00",
+  "path": "/nix/store/lkgidjs90m435m46zqyxa1sphsqfj6ld-nixpkgs-channels",
+  "sha256": "0ww70kl08rpcsxb9xdx8m48vz41dpss4hh3vvsmswll35l158x0v",
+  "fetchSubmodules": false,
+  "deepClone": false,
+  "leaveDotGit": false
+}

nix/pkgs.nix

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+{ java }:
+
+let
+  hostPkgs = import <nixpkgs> { };
+  pinnedVersion = hostPkgs.lib.importJSON ./nixpkgs-version.json;
+  pinnedPkgs = hostPkgs.fetchFromGitHub {
+    owner = "NixOS";
+    repo = "nixpkgs-channels";
+    inherit (pinnedVersion) rev sha256;
+  };
+  config = {
+    packageOverrides = p: {
+      sbt = p.sbt.override {
+        jre = p.${java};
+      };
+    };
+  };
+in
+import pinnedPkgs { inherit config; }

shell.nix

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+let
+  java = "openjdk8_headless";
+  pkgs = import ./nix/pkgs.nix { inherit java; };
+in
+pkgs.mkShell {
+  buildInputs = [
+    pkgs.git
+    pkgs.${java}
+    pkgs.sbt
+  ];
+}