small fixes

gof/__init__.py

@@ -12,7 +12,7 @@ from graph import \
     Apply, Result, Constant, Value, view_roots
 
 from link import \
-    Linker, LocalLinker, PerformLinker, WrapLinker, Profiler
+    Filter, Linker, LocalLinker, PerformLinker, WrapLinker, Profiler
 
 from op import \
     Op

gof/link.py

@@ -108,7 +108,7 @@ class Linker(object):
 
 
 class Filter(object):
-    def __init__(self, r, storage, readonly = False, strict = False, trace = ()):
+    def __init__(self, r, storage, readonly = False, strict = False):
         self.r = r
         self.type = r.type
         self.storage = storage
@@ -127,6 +127,7 @@ class Filter(object):
         except:
             raise_with_op(self.r)
     data = property(__get, __set)
+    value = property(__get, __set)
     def __str__(self):
         return "<" + str(self.storage[0]) + ">"
     def __repr__(self):

gof/type.py

@@ -49,6 +49,9 @@ class Type(object2):
         """
         raise AbstractFunctionError()
 
+    def c_init(self, name, sub):
+        raise AbstractFunctionError()
+
     def c_extract(self, name, sub):
         """
         The code returned from this function must be templated using