Add default.nix file, for building with Nix

default.nix

@@ -0,0 +1,30 @@
+{ stdenv, fetchgit, cmake, boost, gmp, mpfr, libedit, python, texinfo }:
+
+stdenv.mkDerivation {
+  name = "ledger-3.0.1";
+  version = "3.0.1";
+
+  src = ./.;
+
+  buildInputs = [ cmake boost gmp mpfr libedit python texinfo ];
+
+  # Tests on Darwin are failing
+  doCheck = !stdenv.isDarwin;
+  enableParallelBuilding = true;
+
+  meta = {
+    homepage = "http://ledger-cli.org/";
+    description = "A double-entry accounting system with a command-line reporting interface";
+    license = "BSD";
+
+    longDescription = ''
+      Ledger is a powerful, double-entry accounting system that is accessed
+      from the UNIX command-line. This may put off some users, as there is
+      no flashy UI, but for those who want unparalleled reporting access to
+      their data, there really is no alternative.
+    '';
+
+    platforms = stdenv.lib.platforms.all;
+    maintainers = with stdenv.lib.maintainers; [ simons the-kenny ];
+  };
+}