b = [Low, Low, Low, High]
(s, c) = f (a, b)
+-- Not really an adder, but this is nice minimal hardware description
+wire :: Bit -> Bit
+wire a = a
+
+-- Not really an adder either, but a slightly more complex example
+inv :: Bit -> Bit
+inv a = hwnot a
+
+-- Not really an adder either, but a slightly more complex example
+invinv :: Bit -> Bit
+invinv a = hwnot (hwnot a)
+
+-- Not really an adder either, but a slightly more complex example
+dup :: Bit -> (Bit, Bit)
+dup a = (a, a)
+
-- Combinatoric stateless no-carry adder
-- A -> B -> S
no_carry_adder :: (Bit, Bit) -> Bit