Add back *.nix files for the sake of Travis

.gitignore

@@ -3,5 +3,3 @@
 **/#*
 **/.#*
 result
-/default.nix
-/shell.nix

.travis.yml

@@ -4,4 +4,4 @@ env:
 
 language: nix
 
-script: nix-build --argstr compiler "$GHCVERSION"
+script: nix-build build.nix --argstr compiler "$GHCVERSION"

build.nix

@@ -0,0 +1,9 @@
+{ nixpkgs ? import <nixpkgs> {}, compiler ? null }:
+let
+  haskellPackages = if compiler == null
+                    # use the current default version
+                    then nixpkgs.pkgs.haskellPackages
+                    else nixpkgs.pkgs.haskell.packages.${compiler};
+in
+
+haskellPackages.callPackage ./default.nix {}

default.nix

@@ -0,0 +1,27 @@
+{ mkDerivation, ansi-wl-pprint, base, containers, criterion
+, data-fix, deepseq, deriving-compat, parsers, regex-tdfa
+, regex-tdfa-text, semigroups, stdenv, tasty, tasty-hunit, tasty-th
+, text, transformers, trifecta, unordered-containers
+}:
+mkDerivation {
+  pname = "hnix";
+  version = "0.4.0";
+  src = ./.;
+  isLibrary = true;
+  isExecutable = true;
+  libraryHaskellDepends = [
+    ansi-wl-pprint base containers data-fix deepseq deriving-compat
+    parsers regex-tdfa regex-tdfa-text semigroups text transformers
+    trifecta unordered-containers
+  ];
+  executableHaskellDepends = [
+    ansi-wl-pprint base containers data-fix deepseq
+  ];
+  testHaskellDepends = [
+    base containers data-fix tasty tasty-hunit tasty-th text
+  ];
+  benchmarkHaskellDepends = [ base containers criterion text ];
+  homepage = "http://github.com/jwiegley/hnix";
+  description = "Haskell implementation of the Nix language";
+  license = stdenv.lib.licenses.bsd3;
+}

shell.nix

@@ -0,0 +1,45 @@
+{ nixpkgs ? import <darwin> {}, compiler ? "default", doBenchmark ? false }:
+
+let
+
+  inherit (nixpkgs) pkgs;
+
+  f = { mkDerivation, ansi-wl-pprint, base, containers, criterion
+      , data-fix, deepseq, deriving-compat, parsers, regex-tdfa
+      , regex-tdfa-text, semigroups, stdenv, tasty, tasty-hunit, tasty-th
+      , text, transformers, trifecta, unordered-containers
+      }:
+      mkDerivation {
+        pname = "hnix";
+        version = "0.4.0";
+        src = ./.;
+        isLibrary = true;
+        isExecutable = true;
+        libraryHaskellDepends = [
+          ansi-wl-pprint base containers data-fix deepseq deriving-compat
+          parsers regex-tdfa regex-tdfa-text semigroups text transformers
+          trifecta unordered-containers
+        ];
+        executableHaskellDepends = [
+          ansi-wl-pprint base containers data-fix deepseq
+        ];
+        testHaskellDepends = [
+          base containers data-fix tasty tasty-hunit tasty-th text
+        ];
+        benchmarkHaskellDepends = [ base containers criterion text ];
+        homepage = "http://github.com/jwiegley/hnix";
+        description = "Haskell implementation of the Nix language";
+        license = stdenv.lib.licenses.bsd3;
+      };
+
+  haskellPackages = if compiler == "default"
+                       then pkgs.haskellPackages
+                       else pkgs.haskell.packages.${compiler};
+
+  variant = if doBenchmark then pkgs.haskell.lib.doBenchmark else pkgs.lib.id;
+
+  drv = variant (haskellPackages.callPackage f {});
+
+in
+
+  if pkgs.lib.inNixShell then drv.env else drv