ocaml

I want to write a function that takes in a sequence <1,1,2,2,3> and returns the sequence with equal elements grouped like <<1,1>, <2,2>, <3>>. I'm using sequences, not lists, but some of the functions are similar. Some of the functions I am thinking of using are map, reduce, tabulate, filter, append etc.. Reduce takes in an associative function and returns the sequence that is "reduced" by that operator. So, reduce op+ 0 <1,2,3> = 6. My first thought was to use map to raise the sequence by one level. So, <1,1,2,2,3> => <<1>,<1>,<2>,<2>,<3>>. Then, I was thinking of using reduce, in which I

I have a very short test file: let print_backtrace () = try raise Not_found with Not_found -> Printexc.print_backtrace stdout;; let f () = print_backtrace (); Printf.printf "this is to make f non-tail-recursive\n";; f (); I compile and run: % ocamlc -g test.ml % OCAMLRUNPARAM=b ./a.out Raised at file "test.ml", line 1, characters 35-44 this is to make f non-tail-recursive Why isn't f listed in the stack trace? How can I write a function that will print a stack trace of the location it's called from? Here is the code to do what I suggested. I recommend using ocamldebug if at all possible, this

In C++ I'd write bool positive (int a) { #ifdef DEBUG cout << "Checking the number " << a << "\n"; #endif return a > 0; } In OCaml I could write let positive x = begin printf "Checking the number %d\n" x; x > 0 end But how can I disable the printf statement when not in debug mode? you can use cppo : https://github.com/mjambon/cppo . This is available via opam, and offers C like preprocessor features. Without preprocessing you can simply have a global flag defined as let debug = true and write: if debug then printf ...; This code is removed by ocamlopt if debug is false. That said, it's

I'm currently programming an OCaml module defining a type corresponding to a CPU register. The interface of this module is the following : (* * Defines a type which represents a R3000 register. *) type t = | R0 (* Always 0 *) | AT (* Assembler temporary *) | V0 | V1 (* Subroutine return values *) | A0 | A1 | A2 | A3 (* Subroutine arguments *) | T0 | T1 | T2 | T3 | T4 | T5 | T6 | T7 (* Temporary registers *) | S0 | S1 | S2 | S3 | S4 | S5 | S6 | S7 (* Register variables *) | T8 | T9 (* Temporary registers *) | K0 | K1 (* Reserved for kernels *) | GP | SP | FP (* Global/Stack/Frame pointer *) |

I want to read some numbers from a file, take them to a list and finally display them on the screen. numbers.txt currently has 2 3 5 7 11 however as output i'am getting 11 7 5 3 2 - : unit = () Why is this happening? let rec int_list_from_sb sb n = match n with | 0 -> []; | _ -> (bscanf sb " %d" (fun a -> a))::(int_list_from_sb sb (n - 1));; let file_name = open_in "numbers.txt" in let sb = Scanning.from_channel file_name in let int_list = int_list_from_sb sb 5 in List.iter (fun a -> print_int a) int_list;; The order of evaluation of arguments is unspecified in OCaml. So when you do f x :: g y

I wanted to see the type of the multiplication function (*), so I tapped it into the OCaml toplevel. # (*) However, the toplevel echoed: (*);; 1: this is the start of a comment. and then consumed any further input I put in. I figured that I had to get out of the comment mode by pressing Ctrl+d to send EOF. Great. But surely, I should be able to query the type of any function, including our mysterious multiplication function (*) ?! I would be incredibly disappointed if that is a limitation of the toplevel. It does recognize *) as the end of the comment, but it's still waiting for the end of the

I want to create 3-dimensional array in ocaml. Here's what I tried to do: let dp = Array.make n (Array.make n (Array.make k (-1)) However it doesn't work - changing a value dp[0][0][0] changes all values dp[i][j][0]. So how to create matrix with distinct arrays, not with copies of the same one? Array.make n v will just replicate the second argument n times. In other words, it will assign it in a cycle to each element. Since arrays (as well as all other heap-allocated values) are passed by reference, all cells will point to the same array. You need to use the Array.init function, that will call

I am new to Ocaml and trying to write some small example application. I am using ocamlc version 3.11.2 under Linux Ubuntu 10.04. I want to compile two files: a.ml b.ml File b.ml uses definitions from a.ml . As far as I understand, I can use ocamlc -c to perform compilation only. I can call ocamlc one final time when I have all the .cmo files to link them to an executable. Also, when compiling a file that uses definitions from another file, I have to tell the compiler in which .cmi file to find the external definitions. So my idea was to use: ocamlc -i -c a.ml > a.mli ocamlc -c a.mli b.ml