section ‹Sequences as Lists› theory Sequences imports Main begin locale Sequences begin text ‹We reverse the order of application of @{term "(#)"} and @{term "(@)"} because it we think that it is easier to think of sequences as growing to the right.› no_notation Cons (infixr ‹#› 65) abbreviation Append (infixl ‹#› 65) where "Append xs x ≡ Cons x xs" no_notation append (infixr ‹@› 65) abbreviation Concat (infixl ‹@› 65) where "Concat xs ys ≡ append ys xs" end end