haskell-opencv.nix: filter out sources which aren't needed for building

Author: basvandijk

haskell-opencv.nix

@@ -1,5 +1,6 @@
 { mkDerivation
 , stdenv
+, lib
 
 , opencv3_1
 
@@ -36,7 +37,32 @@
 mkDerivation {
   pname = "opencv";
   version = "0.0.0";
-  src = ./.;
+  src = builtins.filterSource (path: type:
+          # Filter out .cpp files under ./src generated by inline-c:
+            !(lib.hasPrefix (toString (./. + "/src")) (dirOf path)
+              && lib.hasSuffix ".cpp" (baseNameOf path))
+
+          # Filter out generated images:
+          && !(  type != "directory"
+              && (  (lib.hasSuffix "doc/generated"          (dirOf path))
+                 || (lib.hasSuffix "doc/generated/examples" (dirOf path))
+                 )
+              )
+
+          # Filter out .nix files so that changing them doesn't necessarily cause a rebuild:
+          && !(lib.hasSuffix ".nix" (baseNameOf path))
+
+          # Filter out some other files or directories not needed for a build:
+          && !(builtins.elem (toString path) (map (p: toString (./. + "/${p}")) [
+                "cabal.config"
+                "Makefile"
+                "README.md"
+                ".git"
+                ".gitignore"
+                "examples"
+                "dist"
+              ]))
+        ) ./.;
 
   libraryHaskellDepends = [
     aeson
@@ -78,10 +104,6 @@ mkDerivation {
       "--with-ld=g++"
     ];
 
-  preConfigure = ''
-    rm -rf dist
-  '';
-
   homepage = "https://github.com/LumiGuide/haskell-opencv";
   license = stdenv.lib.licenses.bsd3;
   maintainers = [ "[email protected]" ];