From 71c4b4a24640a0bc593527660bda16f61e729cc0 Mon Sep 17 00:00:00 2001
From: Krasimir Angelov <kr.angelov@gmail.com>
Date: Mon, 4 Sep 2017 14:49:44 +0200
Subject: instance Eq Expr in the Haskell binding

---
 src/runtime/haskell-bind/PGF2/Expr.hsc | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'src/runtime/haskell-bind')

diff --git a/src/runtime/haskell-bind/PGF2/Expr.hsc b/src/runtime/haskell-bind/PGF2/Expr.hsc
index af3afeef5..a03a24be3 100644
--- a/src/runtime/haskell-bind/PGF2/Expr.hsc
+++ b/src/runtime/haskell-bind/PGF2/Expr.hsc
@@ -34,6 +34,13 @@ data Expr = Expr {expr :: PgfExpr, touchExpr :: Touch}
 instance Show Expr where
   show = showExpr []
 
+instance Eq Expr where
+  (Expr e1 e1_touch) == (Expr e2 e2_touch) = 
+    unsafePerformIO $ do
+      res <- pgf_expr_eq e1 e2
+      e1_touch >> e2_touch
+      return (res /= 0)
+
 -- | Constructs an expression by lambda abstraction
 mkAbs :: BindType -> CId -> Expr -> Expr
 mkAbs bind_type var (Expr body bodyTouch) =
-- 
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