gistfile1.txt

diff --git a/firedrake/parloops.py b/firedrake/parloops.py
index 037f0cc..b198056 100644
--- a/firedrake/parloops.py
+++ b/firedrake/parloops.py
@@ -89,7 +89,7 @@ def _form_kernel(kernel, measure, args, **kwargs):
                         "par_loop_kernel", **kwargs)
 
 
-def par_loop(kernel, measure, args, **kwargs):
+def par_loop(kernel, measure, args, return_callable=False, **kwargs):
     """A :func:`par_loop` is a user-defined operation which reads and
     writes :class:`.Function`\s by looping over the mesh cells or facets
     and accessing the degrees of freedom on adjacent entities.
@@ -238,4 +238,7 @@ def par_loop(kernel, measure, args, **kwargs):
         return f.dat(intent, _map['nodes'](f))
     op2args += [mkarg(func, intent) for (func, intent) in args.itervalues()]
 
-    return pyop2.par_loop(*op2args)
+    if return_callable:
+        return lambda: pyop2.par_loop(op2args)
+    else:
+        return pyop2.par_loop(*op2args)