install required data files with the binary

Author: layus

hnix.cabal

@@ -11,9 +11,19 @@ license:        BSD3
 license-file:   LICENSE
 build-type:     Simple
 cabal-version:  >= 1.10
+data-dir:       data/
+data-files:
+    nix/corepkgs/buildenv.nix
+    nix/corepkgs/unpack-channel.nix
+    nix/corepkgs/derivation.nix
+    nix/corepkgs/fetchurl.nix
+    nix/corepkgs/imported-drv-to-derivation.nix
 extra-source-files:
     data/nix/corepkgs/buildenv.nix
+    data/nix/corepkgs/unpack-channel.nix
     data/nix/corepkgs/derivation.nix
+    data/nix/corepkgs/fetchurl.nix
+    data/nix/corepkgs/imported-drv-to-derivation.nix
     data/nix/tests/lang/binary-data
     data/nix/tests/lang/data
     data/nix/tests/lang/dir1/a.nix