Add top-level __valueSize

Fixes #253

default.nix

@@ -22,6 +22,16 @@ let inherit (nixpkgs) pkgs;
                   then doJailbreak super.compact
                   else super.compact;
       serialise = dontCheck super.serialise;
+      ghc-datasize =
+        pkgs.haskell.lib.overrideCabal super.ghc-datasize (attrs: {
+          enableLibraryProfiling    = false;
+          enableExecutableProfiling = false;
+        });
+      ghc-heap-view =
+        pkgs.haskell.lib.overrideCabal super.ghc-heap-view (attrs: {
+          enableLibraryProfiling    = false;
+          enableExecutableProfiling = false;
+        });
     };
   };
 

hnix.cabal

@@ -2,7 +2,7 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 760d308ea1a1df341e0191fee145518d3901d2eef3e8c4ee7c1f43a3de3acaad
+-- hash: 0ae6db7ef792f86593ae6684bf7ab48b8e79cc147213ef6ab88475c142f9507a
 
 name:           hnix
 version:        0.5.0
@@ -94,6 +94,7 @@ library
     , directory
     , exceptions
     , filepath
+    , ghc-datasize
     , hashable
     , haskeline
     , megaparsec

package.yaml

@@ -68,6 +68,7 @@ library:
     - cryptohash
     - deriving-compat           >= 0.3 && < 0.5
     - directory
+    - ghc-datasize
     - hashable
     - haskeline
     - megaparsec

src/Nix/Builtins.hs

@@ -191,7 +191,7 @@ builtinsList = sequence [
     , add  Normal   "typeOf"                     typeOf
     , add  Normal   "unsafeDiscardStringContext" unsafeDiscardStringContext
     , add2 Normal   "unsafeGetAttrPos"           unsafeGetAttrPos
-
+    , add  TopLevel "__valueSize"                getRecursiveSize
   ]
   where
     wrap t n f = Builtin t (n, f)

src/Nix/Effects.hs

@@ -30,3 +30,5 @@ class MonadFile m => MonadEffects m where
     derivationStrict :: NValue m -> m (NValue m)
 
     nixInstantiateExpr :: String -> m (NValue m)
+
+    getRecursiveSize :: a -> m (NValue m)

src/Nix/Exec.hs

@@ -1,5 +1,6 @@
 {-# LANGUAGE AllowAmbiguousTypes #-}
 {-# LANGUAGE ApplicativeDo #-}
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE FlexibleContexts #-}
@@ -73,6 +74,10 @@ import           System.Process (readProcessWithExitCode)
 import           Text.PrettyPrint.ANSI.Leijen (text)
 import qualified Text.PrettyPrint.ANSI.Leijen as P
 
+#if MIN_VERSION_ghc_datasize(0,2,0)
+import           GHC.DataSize
+#endif
+
 type MonadNix e m =
     (Scoped e (NThunk m) m, Framed e m, Has e SrcSpan, Has e Options,
      Typeable m, MonadVar m, MonadEffects m, MonadFix m, MonadCatch m,
@@ -552,6 +557,13 @@ instance (MonadFix m, MonadCatch m, MonadThrow m, MonadIO m,
                 Success v -> evalExprLoc v
             err -> throwError $ "nix-instantiate failed: " ++ show err
 
+    getRecursiveSize =
+#if MIN_VERSION_ghc_datasize(0,2,0)
+        toNix @Integer <=< fmap fromIntegral . liftIO . recursiveSize
+#else
+        toNix (0 :: Integer)
+#endif
+
 runLazyM :: Options -> MonadIO m => Lazy m a -> m a
 runLazyM opts = (`evalStateT` M.empty)
               . (`runReaderT` newContext opts)