diff --git a/src/mapper/__init__.py b/src/mapper/__init__.py
index be2409532ed0ec16c41cd5aed2d79b77ea18c865..691ea71f188ca159e67750e81c2e15d29583d77d 100644
--- a/src/mapper/__init__.py
+++ b/src/mapper/__init__.py
@@ -1,3 +1,15 @@
+try:
+    import numpy
+
+    def is_numpy_array(val):
+        return isinstance(val, numpy.ndarray)
+except ImportError:
+    def is_numpy_array(ary):
+        return False
+
+
+
+
 class Mapper(object):
     def __init__(self, recurse=True):
         self.Recurse = True
@@ -40,6 +52,8 @@ class Mapper(object):
             return self.map_constant(expr, *args, **kwargs)
         elif isinstance(expr, list):
             return self.map_list(expr, *args, **kwargs)
+        elif is_numpy_array(expr):
+            return self.map_numpy_array(expr, *args, **kwargs)
         else:
             raise ValueError, "encountered invalid foreign object: %s" % repr(expr)
 
@@ -108,6 +122,8 @@ class CombineMapper(RecursiveMapper):
     map_list = map_sum
     map_vector = map_sum
 
+    def map_numpy_array(self, expr):
+        return self.combine(expr.flat)
 
 
 
@@ -158,17 +174,21 @@ class IdentityMapperBase(object):
                               ((exp, self.rec(coeff, *args, **kwargs))
                                   for exp, coeff in expr.data))
 
-
     map_list = map_sum
     map_vector = map_sum
 
+    def map_numpy_array(self, expr):
+        import numpy
+        result = numpy.empty(expr.shape, dtype=object)
+        from pytools import indices_in_shape
+        for i in indices_in_shape(expr.shape):
+            result[i] = self.rec(expr[i])
+        return result
 
 
 
 class IdentityMapper(IdentityMapperBase, RecursiveMapper):
-    def handle_unsupported_expression(self, expr, *args, **kwargs):
-        return expr
+    pass
 
 class NonrecursiveIdentityMapper(IdentityMapperBase, Mapper):
-    def handle_unsupported_expression(self, expr, *args, **kwargs):
-        return expr
+    pass
diff --git a/src/mapper/constant_folder.py b/src/mapper/constant_folder.py
index 69acbb2c6e2e407fc826e54cd28163e165662957..5da8218bbb1b1a54f6a47b24f881c0e8f13c4549 100644
--- a/src/mapper/constant_folder.py
+++ b/src/mapper/constant_folder.py
@@ -34,6 +34,9 @@ class ConstantFoldingMapperBase(object):
 
         return self.fold(expr, Sum, operator.add, Sum)
 
+    def handle_unsupported_expression(self, expr):
+        return expr
+
 
 
 class CommutativeConstantFoldingMapperBase(ConstantFoldingMapperBase):
diff --git a/src/mapper/evaluator.py b/src/mapper/evaluator.py
index 30cbb55f7757a0c2e582190c6ace59a36fb30718..4ff148c735ddfbc6583e5846afed838b5d5a4a1d 100644
--- a/src/mapper/evaluator.py
+++ b/src/mapper/evaluator.py
@@ -68,8 +68,15 @@ class EvaluationMapper(RecursiveMapper):
         return result
 
     def map_list(self, expr):
-        return [self.rec(child) for child in expr.Children]
-
+        return [self.rec(child) for child in expr]
+
+    def map_numpy_array(self, expr):
+        import numpy
+        result = numpy.empty(expr.shape, dtype=object)
+        from pytools import indices_in_shape
+        for i in indices_in_shape(expr.shape):
+            result[i] = self.rec(expr[i])
+        return result
 
 
 
diff --git a/src/mapper/expander.py b/src/mapper/expander.py
index 6978bc76b20765c63447bbcd2f8a9eef539fe2d9..0822075333fa286a1c9792f5e29fc5acfa688306 100644
--- a/src/mapper/expander.py
+++ b/src/mapper/expander.py
@@ -66,6 +66,8 @@ class ExpandMapper(IdentityMapper):
         else:
             return IdentitityMapper.map_power(expr)
 
+    def handle_unsupported_expression(self, expr):
+        return expr