From a5fe5b9378937a35fa7921c6ed62ec9efa059934 Mon Sep 17 00:00:00 2001
From: Krasimir Angelov <kr.angelov@gmail.com>
Date: Tue, 5 Sep 2017 09:46:43 +0200
Subject: [PATCH] added exprHash in the Haskell binding

---
 src/runtime/haskell-bind/PGF2.hsc    | 10 ++++++++++
 src/runtime/haskell-bind/PGF2/FFI.hs |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/src/runtime/haskell-bind/PGF2.hsc b/src/runtime/haskell-bind/PGF2.hsc
index 037145ee6..f2f1b4113 100644
--- a/src/runtime/haskell-bind/PGF2.hsc
+++ b/src/runtime/haskell-bind/PGF2.hsc
@@ -39,6 +39,7 @@ module PGF2 (-- * PGF
              mkFloat,unFloat,
              mkMeta,unMeta,
              mkCId,
+             exprHash,
              treeProbability,
 
              -- ** Types
@@ -323,6 +324,15 @@ treeProbability (PGF p _) (Expr c_expr touch1) =
     touch1
     return (realToFrac res)
 
+exprHash :: Int32 -> Expr -> Int32
+exprHash h (Expr c_expr touch1) =
+  unsafePerformIO $ do
+    h <- pgf_expr_hash (fromIntegral h) c_expr
+    touch1
+    return (fromIntegral h)
+
+    
+
 -----------------------------------------------------------------------------
 -- Graphviz
 
diff --git a/src/runtime/haskell-bind/PGF2/FFI.hs b/src/runtime/haskell-bind/PGF2/FFI.hs
index 3870e2fba..ce4dd6983 100644
--- a/src/runtime/haskell-bind/PGF2/FFI.hs
+++ b/src/runtime/haskell-bind/PGF2/FFI.hs
@@ -328,6 +328,9 @@ foreign import ccall "pgf/expr.h pgf_expr_arity"
 foreign import ccall "pgf/expr.h pgf_expr_eq"
   pgf_expr_eq :: PgfExpr -> PgfExpr -> IO CInt
 
+foreign import ccall "pgf/expr.h pgf_expr_hash"
+  pgf_expr_hash :: Word -> PgfExpr -> IO Word
+
 foreign import ccall "pgf/expr.h pgf_compute_tree_probability"
   pgf_compute_tree_probability :: Ptr PgfPGF -> PgfExpr -> IO CFloat