# answers.ml

Download file: answers.ml
`(*** Keep these lines. ***) let qfile = "qqs.ml" ;; let formatter = Format.(make_formatter (fun _ _ _ -> ()) (fun () -> ())) ;; Topdirs.dir_use formatter (if Sys.file_exists qfile then qfile else Sys.getenv "HOME" ^ "/Exam-OCaml/" ^ qfile) ;; (************************************) (***** QUESTION 1 *****) let f1 f tos x = try tos (f x) with _ -> "exception" ;; (* ✔✔✔ Check your answer - keep the following line untouched. If you get a type error here, it means that your function f1 does not have the expected type. *) let () = q1 { ff = f1 } ;; (***** QUESTION 2 *****) let f2 a b l = (* Ignore part until b *) let rec loop2 acu = function | [] -> List.rev acu | x :: xs -> if x = b then List.rev (List.rev_append xs acu) else loop2 acu xs in (* Keep first part until a *) let rec loop1 acu = function | [] -> List.rev acu | x :: xs -> if x = a then loop2 acu xs else loop1 (x :: acu) xs in loop1 [] l ;; (* ✔✔✔ Check your answer - keep the following line untouched. If you get a type error here, it means that your function f2 does not have the expected type. *) let () = q2 { ff = f2 } ;; (***** QUESTION 3 *****) let f3 (Node (x,_) as tree) = let rec loop acu (Node (x, l)) = List.fold_left loop (max x acu) l in loop x tree ;; (* ✔✔✔ Check your answer - keep the following line untouched. If you get a type error here, it means that your function f3 does not have the expected type. *) let () = q3 { ff = f3 } ;; (***** QUESTION 4 *****) let f4 = { forbid = (fun (a,b) -> if a = b then "equal" else "") ; f = (fun (a,b) -> a < b) } ;; (* ✔✔✔ Check your answer - keep the following line untouched. If you get a type error here, it means that your function f4 does not have the expected type. *) let () = q4 { ff = f4 } ;; (***** QUESTION 5 *****) let f5 f = { forbid = (function None -> "" | Some x -> f.forbid x) ; f = (function None -> false | Some x -> f.f x) } ;; (* ✔✔✔ Check your answer - keep the following line untouched. If you get a type error here, it means that your function f5 does not have the expected type. *) let () = q5 { ff = f5 } ;; (***** QUESTION 6 *****) let f6 f = let forbid l = if l = [] then "" else if List.for_all (fun x -> f.forbid x <> "") l then "all" else "" and f l = List.exists (fun x -> f.forbid x = "" && f.f x) l in { forbid ; f } ;; (* ✔✔✔ Check your answer - keep the following line untouched. If you get a type error here, it means that your function f6 does not have the expected type. *) let () = q6 { ff = f6 } ;; (***** QUESTION 7 *****) let f7 x graph = let rec loop acu x = let succ = List.filter_map (fun (a,b) -> if a = x then Some b else None) graph in if List.mem x acu then acu else List.fold_left (fun acu y -> loop acu y) (x :: acu) succ in loop [] x ;; (* ✔✔✔ Check your answer - keep the following line untouched. If you get a type error here, it means that your function f7 does not have the expected type. *) let () = q7 { ff = f7 } ;;`