shell repro

cabal.project

@@ -7,4 +7,5 @@ package dummy-app
 source-repository-package
   type: git
   location: http://github.com/well-typed/canonical-json
-  tag: ddfe3593b80b5ceb88842bb7a6f2268df75d2c2f
+  tag: ddfe3593b80b5ceb88842bb7a6f2268df75d2c2f
+  --sha256: 02fzn1xskis1lc1pkz0j92v6ipd89ww0k2p3dvwpm3yap5dpnm7k

dummy-app/app/dummy-app.hs

@@ -1,2 +1,2 @@
 main :: IO ()
-main = undefined
+main = return ()

shell.nix

@@ -0,0 +1,15 @@
+let
+  lib = import ./nix/lib.nix;
+  pkgs = lib.pkgs;
+  hsPkgs = import ./default.nix { };
+in
+hsPkgs.shellFor {
+  packages = ps: with ps; [
+    dummy-app
+  ];
+  withHoogle = true;
+  buildInputs = with pkgs.haskellPackages;
+    [ hlint stylish-haskell ghcid lib.niv lib.pkgs.haskell-nix.cabal-install ];
+  exactDeps = true;
+
+}