Double_comma.ml

let pp = Printf.printf
module Explanation = struct
pp "At the begining of a module (or the beginning of the file),";
pp "we start in execution mode\n.";
pp "We can have a" ;
pp "comma separated list of expression which is evaluted";
pp "at the top-level of the module.\n"

open List [@@remark "This is not an expression: we exit evalation mode" ] 

let we_enter_definition_mode =
  pp "comma separated sequence of exrepssion";
  pp "are still possible in definition mode" ;
  pp "but they necessarily belongs to an enclosing let or module binding.\n";
  true

module M = struct
  pp "Inside a new module,";
  pp "we start once again, in execution mode.\n"
end

let after_exiting_M =
  pp "we are back to definition mode";
  true

let how_to_go_back_to_execution_mode = pp "Double comma are the only way.\n";;

pp "Here, we are back to execution mode\n";
pp "and evaluate one sequence of expression.\n"

let () =
  pp "It is also perfectly possible to avoid completely the use of ;;";
  pp {|by enclosing all sequence "s_1;..s_n" inside an "let () = s_1;..s_n " construction|} 
end