CODEWITHSUNDEEP
ocamlutop
Mars
Mars

Reputation: 8854

Change utop output width

When displaying long lists and other large values, utop wraps them at about 80 columns, even when my terminal window is wider. How can I change the output width?

The only thing that I have found that might have provided the solution is UTop.size, which has type LTerm_geom.size React.signal, and seems to correctly record the size of my terminal window. In this example my terminal window had dimensions 164x37:

# #require "react";;
# #require "lambda-term";;
# React.S.value UTop.size;;
- : LTerm_geom.size = {LTerm_geom.rows = 37; cols = 164}

However, the value of cols doesn't seem to affect how values are displayed. For example, this is copied from the same session (with line breaks as they were displayed):

# List.hd algs;;
- : (int list * float) list =
[([2; 1; 0], 1.); ([2; 1], 0.54148398267); ([2; 0], 0.677137905076);
 ([2], 0.218621887745); ([1; 0], 0.781378112255); ([1], 0.322862094924);
 ([0], 0.45851601733); ([], 0.)]

Upvotes: 2

Views: 266

Answers (1)

Anton Trunov
Anton Trunov

Reputation: 15404

There is a function called UTop.set_margin_function:

μ> #typeof "UTop.set_margin_function";;
val UTop.set_margin_function : (LTerm_geom.size -> int option) -> unit

Here is a simplistic example usage:

μ> UTop.set_margin_function (fun _ -> Some 150);;

After this point utop will use about 150 columns for printing out the results.

Here is an example session (shell + utop):

> utop -version
The universal toplevel for OCaml, version 1.19.3, compiled for OCaml version 4.04.1

> cat ~/.ocamlinit
(* Added by OPAM. *)
let () =
  try Topdirs.dir_directory (Sys.getenv "OCAML_TOPLEVEL_PATH")
  with Not_found -> ()
;;

> cat ~/.utoprc
cat: .utoprc: No such file or directory

> utop

utop # gen_nat_list 1 50;;   (* gen_nat_list is some test function *)
- : int list =
[1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22;
23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41;
42; 43; 44; 45; 46; 47; 48; 49; 50]

utop # UTop.set_margin_function (fun _ -> Some 150);;

utop # gen_nat_ist 1 50;;
- : int list =
[1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39;
 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50]

Upvotes: 2

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