Hi, Is there a way to get this to typecheck?
(: cars : (All (A) (Listof (Listof A)) -> (Listof A))) (define (cars ls) (map car (filter cons? ls))) By looking at the error, it seems the problem is that it is impossible to map car on a list of lists: > (map car '((1))) Type Checker: Polymorphic function map could not be applied to arguments... Thanks, -- Éric ____________________ Racket Users list: http://lists.racket-lang.org/users
