Ok, I wrote this one when I was listening to a lecture on databases and data warehouses - I was exploring functional programming at the time, and decided that if you really thought about it you could make a very nice and pleasant function that does almost absolutely nothing, apart from being aesthetically pleasing. After I wrote one on paper, I decided that it could be expanded a bit, but it was too much hassle to do by hand... so, a generator!
What this program does is actually generate a program, which, upon running will recursively pass all its parameters to itself, and when the recursion stops it will use the first of the parameters as a function, supplying it with the other parameters as parameters... is this clear? I suppose an example is in order...
Ok, so first, I run the program in the following way:
ocaml dada_gen.ml 5 f a b c > dada_ex.ml
...and got the following code as a result (in the file dada_ex.ml):
1 let f a b c =
2 let f a b c =
3 let f a b c =
4 let f a b c =
5 let f a b c =
6 let f a b c =
7 a b c
8 in f a b c
9 in f a b c
10 in f a b c
11 in f a b c
12 in f a b c
13;;
14
2 let f a b c =
3 let f a b c =
4 let f a b c =
5 let f a b c =
6 let f a b c =
7 a b c
8 in f a b c
9 in f a b c
10 in f a b c
11 in f a b c
12 in f a b c
13;;
14
Ok, then I run the Ocaml top-level like this:
ocaml
Inside the toplevel I loaded the file:
#use "dada_ex.ml";;
...and got the response:
val f : ('a -> 'b -> 'c) -> 'a -> 'b -> 'c = <fun>
...and then the function f funtion like this:
f (+) 2 2
...and got in return:
- : int = 4
...which just means that the result is 4. I could've achieved the same by going:
(+) 2 2;;
...or even
2 + 2
That's why its dada. It's not meant to be useful!
Yeah, I know, I'm weird.
Here's the script:
1 (**
2 * Dada generator
3 * Generates a completely useless but aesthetically pleasing dada program
4 *
5 * Potential issues:
6 * None
7 * Parameters:
8 * number of internal functions
9 * name of the dadaistic function
10 * list of passed parameters
11 * Requires:
12 * Ocaml (http://caml.inria.fr/)
13 * Sense of humor
14 *)
15
16(**
17 * Function responsible for generating dadaistic programs basing on the
18 * supplied parameters
19 * @param function_name the name of the main function
20 * @param parameter_list a list of strings which will be inserted as the
21 * body of the inner-most function
22 * @param nested_function_count the number of functions generated inside
23 * the main function
24 * @author Konrad Siek
25 *)
26let generate_dada function_name parameter_list nested_function_count =
27 let rec list_to_string list =
28 match list with
29 | head::tail -> head ^ " " ^ (list_to_string tail)
30 | [] -> ""
31 in
32 let rec tabs count =
33 if count = 0 then
34 ""
35 else
36 " " ^ (tabs (count - 1))
37 in
38 let program = ref ("let " ^ function_name ^ " " ^
39 (list_to_string parameter_list) ^ "=\n") in
40 let _ = for i = 1 to nested_function_count do
41 program := !program ^ (tabs i);
42 program := !program ^ "let " ^ function_name ^ " " ^
43 (list_to_string parameter_list) ^ "=\n"
44 done in
45 program := !program ^ (tabs (nested_function_count + 1)) ^
46 (list_to_string parameter_list) ^ "\n";
47 let _ = for i = nested_function_count downto 1 do
48 program := !program ^ (tabs i);
49 program := !program ^ "in " ^ function_name ^ " " ^
50 (list_to_string parameter_list) ^ "\n"
51 done in
52 program := !program ^ ";;\n";
53 !program
54;;
55
56(* Main method calling the generation function. *)
57if Array.length Sys.argv > 3 then
58 let count = int_of_string Sys.argv.(1) in
59 let function_name = Sys.argv.(2) in
60 let parameters = Array.to_list
61 (Array.sub Sys.argv 3 (Array.length Sys.argv - 3)) in
62 let program = generate_dada function_name parameters count in
63 print_endline program
64else
65 print_endline ("Usage:\n\t" ^ Sys.argv.(0) ^ " <function_count> " ^
66 "<main_function_name> <parameter> [ ... <parameter> ]")
67;;
2 * Dada generator
3 * Generates a completely useless but aesthetically pleasing dada program
4 *
5 * Potential issues:
6 * None
7 * Parameters:
8 * number of internal functions
9 * name of the dadaistic function
10 * list of passed parameters
11 * Requires:
12 * Ocaml (http://caml.inria.fr/)
13 * Sense of humor
14 *)
15
16(**
17 * Function responsible for generating dadaistic programs basing on the
18 * supplied parameters
19 * @param function_name the name of the main function
20 * @param parameter_list a list of strings which will be inserted as the
21 * body of the inner-most function
22 * @param nested_function_count the number of functions generated inside
23 * the main function
24 * @author Konrad Siek
25 *)
26let generate_dada function_name parameter_list nested_function_count =
27 let rec list_to_string list =
28 match list with
29 | head::tail -> head ^ " " ^ (list_to_string tail)
30 | [] -> ""
31 in
32 let rec tabs count =
33 if count = 0 then
34 ""
35 else
36 " " ^ (tabs (count - 1))
37 in
38 let program = ref ("let " ^ function_name ^ " " ^
39 (list_to_string parameter_list) ^ "=\n") in
40 let _ = for i = 1 to nested_function_count do
41 program := !program ^ (tabs i);
42 program := !program ^ "let " ^ function_name ^ " " ^
43 (list_to_string parameter_list) ^ "=\n"
44 done in
45 program := !program ^ (tabs (nested_function_count + 1)) ^
46 (list_to_string parameter_list) ^ "\n";
47 let _ = for i = nested_function_count downto 1 do
48 program := !program ^ (tabs i);
49 program := !program ^ "in " ^ function_name ^ " " ^
50 (list_to_string parameter_list) ^ "\n"
51 done in
52 program := !program ^ ";;\n";
53 !program
54;;
55
56(* Main method calling the generation function. *)
57if Array.length Sys.argv > 3 then
58 let count = int_of_string Sys.argv.(1) in
59 let function_name = Sys.argv.(2) in
60 let parameters = Array.to_list
61 (Array.sub Sys.argv 3 (Array.length Sys.argv - 3)) in
62 let program = generate_dada function_name parameters count in
63 print_endline program
64else
65 print_endline ("Usage:\n\t" ^ Sys.argv.(0) ^ " <function_count> " ^
66 "<main_function_name> <parameter> [ ... <parameter> ]")
67;;
The code is also available at GitHub as ocaml/dada_generator.ml.
