From 3d14ed92702bf58123405f406f82be083a28b959 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Thu, 11 Oct 2007 14:06:43 +0000
Subject: [PATCH] * A primop for calling functions strictly (i.e. forcing
 evaluation of   argument).  Necessary to actually get memoisation of
 functions like   "fib" with maximal laziness.

---
 src/libexpr/primops.cc | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 3d080dec3..129b9e2e5 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -927,6 +927,17 @@ static Expr prim_stringLength(EvalState & state, const ATermVector & args)
 }
 
 
+/*************************************************************
+ * Strictness
+ *************************************************************/
+
+
+static Expr prim_strict(EvalState & state, const ATermVector & args)
+{
+    return evalExpr(state, makeCall(args[0], evalExpr(state, args[1])));
+}
+
+
 /*************************************************************
  * Primop registration
  *************************************************************/
@@ -993,6 +1004,9 @@ void EvalState::addPrimOps()
     addPrimOp("toString", 1, prim_toString);
     addPrimOp("__substring", 3, prim_substring);
     addPrimOp("__stringLength", 1, prim_stringLength);
+
+    // Strictness
+    addPrimOp("strict", 2, prim_strict);
 }