MESG_to_string : (string -> string) ref
STRUCTURE
Feedback
SYNOPSIS
Alterable function for formatting HOL_MESG.
DESCRIPTION
MESG_to_string is a reference to a function for formatting the argument to an application of HOL_MESG.

The default value of MESG_to_string is format_MESG.

EXAMPLE
    - fun alt_MESG_report s = String.concat["Dear HOL user: ", s, "\n"];

    - MESG_to_string := alt_MESG_report;

    - HOL_MESG "Hi there."

    Dear HOL user: Hi there.
    > val it = () : unit

SEEALSO
Feedback, HOL_MESG, format_MESG, ERR_to_string, WARNING_to_string
HOL  Kananaskis-14