70 lines
1.7 KiB
OCaml
70 lines
1.7 KiB
OCaml
let usage args =
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let err = Format.sprintf "usage: %s %s" Sys.argv.(0) args in
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print_endline err;
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exit 1
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let usage_default day = usage (string_of_int day ^ " <part> <infile>")
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let main day mains = function
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| [part; input] -> mains.(int_of_string part - 1) input
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| _ -> usage_default day
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type 'a monoid =
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{id: 'a;
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op: 'a -> 'a -> 'a;
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op_name: string;
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pp: Format.formatter -> 'a -> unit}
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let mult = {id = 1; op = ( * ); op_name = "*"; pp = Format.pp_print_int}
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let add = {id = 0; op = ( + ); op_name = "+"; pp = Format.pp_print_int}
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let fold_list {op; id; _} = List.fold_left op id
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let%test _ = fold_list add [] = 0
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let%test _ = fold_list add [1;2;3;4] = 10
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let%test _ = fold_list mult [1;2;3;4] = 24
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let print_fold ?(format=false) mon xs =
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let res = List.fold_left mon.op mon.id xs in
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let rec go fmt = function
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| [] -> Format.fprintf fmt "%a" mon.pp mon.id
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| [x] -> Format.fprintf fmt "%a" mon.pp x
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| x::xs ->
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let f =
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if format then Format.fprintf fmt "%a %s@ %a"
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else Format.fprintf fmt "%a %s %a" in
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f mon.pp x mon.op_name go xs in
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let f =
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if format then Format.printf "%a =@ %a\n"
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else Format.printf "%a = %a\n" in
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f go xs mon.pp res
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let print_prod ?format = print_fold ?format mult
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let print_sum ?format = print_fold ?format add
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let%expect_test _ =
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print_prod [];
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[%expect{| 1 = 1 |}]
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let%expect_test _ =
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print_prod [1];
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[%expect{| 1 = 1 |}]
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let%expect_test _ =
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print_prod [1;2;3;4];
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[%expect{| 1 * 2 * 3 * 4 = 24 |}]
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let%expect_test _ =
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print_sum [];
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[%expect{| 0 = 0 |}]
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let%expect_test _ =
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print_sum [1];
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[%expect{| 1 = 1 |}]
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let%expect_test _ =
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print_sum [1;2;3;4];
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[%expect{| 1 + 2 + 3 + 4 = 10 |}]
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