2 files changed, 43 insertions, 0 deletions
diff --git a/krebs/5pkgs/haskell/nix-diff/default.nix b/krebs/5pkgs/haskell/nix-diff/default.nix
new file mode 100644
index 000000000..df0315048
--- /dev/null
+++ b/krebs/5pkgs/haskell/nix-diff/default.nix
@@ -0,0 +1,25 @@
+{ mkDerivation, attoparsec, base, containers, Diff, fetchgit, mtl
+, nix-derivation, optparse-generic, stdenv, system-filepath, text
+, unix, vector
+}:
+mkDerivation {
+  pname = "nix-diff";
+  version = "1.0.0-krebs1";
+  src = fetchgit {
+    url = "https://github.com/Gabriel439/nix-diff";
+    sha256 = "1k00nx8pannqmpzadkwfrs6bf79yk22ynhd033z5rsyw0m8fcz9k";
+    rev = "e32ffa2c7f38b47a71325a042c1d887fb46cdf7d";
+  };
+  patches = [
+    ./nixos-system.patch
+  ];
+  isLibrary = false;
+  isExecutable = true;
+  executableHaskellDepends = [
+    attoparsec base containers Diff mtl nix-derivation optparse-generic
+    system-filepath text unix vector
+  ];
+  homepage = "https://github.com/Gabriel439/nix-diff";
+  description = "Explain why two Nix derivations differ";
+  license = stdenv.lib.licenses.bsd3;
+}
diff --git a/krebs/5pkgs/haskell/nix-diff/nixos-system.patch b/krebs/5pkgs/haskell/nix-diff/nixos-system.patch
new file mode 100644
index 000000000..03e186aa9
--- /dev/null
+++ b/krebs/5pkgs/haskell/nix-diff/nixos-system.patch
@@ -0,0 +1,18 @@
+diff --git a/src/Main.hs b/src/Main.hs
+index 959ab8e..d3b6077 100644
+--- a/src/Main.hs
++++ b/src/Main.hs
+@@ -95,7 +95,12 @@ pathToText path =
+     underneath `/nix/store`, but this is the overwhelmingly common use case
+ -}
+ derivationName :: FilePath -> Text
+-derivationName = Data.Text.dropEnd 4 . Data.Text.drop 44 . pathToText
++derivationName p =
++    if Data.Text.isPrefixOf "nixos-system" s
++      then "nixos-system"
++      else s
++  where
++    s = Data.Text.dropEnd 4 . Data.Text.drop 44 . pathToText $ p
+ 
+ -- | Group input derivations by their name
+ groupByName :: Map FilePath (Set Text) -> Map Text (Map FilePath (Set Text))