init with minimal exporting & inputs extending api

de-systemize.nix

@@ -0,0 +1,22 @@
+let
+  l = builtins;
+  /*
+  A helper function which hides the complexities of dealing
+  with 'system' properly from you, while still providing
+  escape hatches when dealing with cross-compilation.
+
+  You can use this function independently of the rest of std.
+  */
+  deSystemize = let
+    iteration = cutoff: system: fragment:
+      if ! (l.isAttrs fragment) || cutoff == 0
+      then fragment
+      else if l.hasAttr "${system}" fragment && ! l.isFunction fragment.${system}
+      then fragment // fragment.${system}
+      else if l.hasAttr "${system}" fragment && l.isFunction fragment.${system}
+      then fragment // {__functor = _: fragment.${system};}
+      else l.mapAttrs (_: iteration (cutoff - 1) system) fragment;
+  in
+    iteration 3;
+in
+  deSystemize