OCaml multiline output issues

Hi everyone, I'm Jeremy, a student who loves OCaml (ahah), and I've got some troubles to perfectly develop myself.

What does not work :

  • Display the answer on several lines
  • Consequently, the debug is impossible with a string appended to the end of the displayed string : smthg like "§RED§ ..."
  • Not just the "print_endline"/"print_newline" functions that don't work, but the "\n" caracter too

What works

  • Validation of puzzles that need an answer on multiple lines

How to see the bug ?

Just test on a puzzle to print several lines by writting prerr_endline "test\ntest", or prerr_string "test"; prerr_newline; prerr_string"test"; prerr_newline, or prerr_string "test\ntest\n" (you can even try it with the print_* correponding functions).

Summary

There is a bug that doesn't allow to correctly display an answer on multiple lines (even with the prerr_endline function (print on the stderr)), and so doesn't allow to debug correctly a puzzle like ASCII ART etc...
Thank you in advance if you can look at it, maybe I'm wrong or I don't know, tell me if it is the case.