Utterly baffling error message

[itamarst]

If you look at ir.py you'll see this code:

class Primitive(NativeType):
    @match(many(lazy("NativeBlock"), min=1))
    def __init__(self, *blocks):
        self.blocks = blocks

If you instantiate ir.Primitive() with no arguments you'll get:

Traceback (most recent call last):
  File "/home/itamarst/Datawire/quark/quarkc/command.py", line 141, in main
    tmp_pkg = IR.load_path(ir_name)
  File "/home/itamarst/Datawire/quark/quarkc/ir.py", line 40, in load_path
    return IR.load(f.read(), source=path)
  File "/home/itamarst/Datawire/quark/quarkc/ir.py", line 46, in load
    ir_e = eval(ir_c, {}, dict((k,g[k]) for k in __all__))
  File "/home/itamarst/.quark/cache/generics.q.ir", line 1718, in <module>
    Local(LocalName('a'), Primitive(), FloatLit(0.0)),
  File "/home/itamarst/Datawire/quark/quarkc/match.py", line 439, in __call__
    return compiled.apply(self.object, *args, **kwargs)
  File "/home/itamarst/Datawire/quark/quarkc/match.py", line 182, in apply
    return state.action(*args, **kwargs)
  File "/home/itamarst/Datawire/quark/quarkc/tree.py", line 77, in __init__
    assert False, "%s is abstract base class" % self.__class__
AssertionError: <class 'quarkc.ir.Primitive'> is abstract base class

which is not helpful in debugging.