# adttest.b## Written in 2018 by David Boddie <david@boddie.org.uk>## To the extent possible under law, the author(s) have dedicated all copyright# and related and neighboring rights to this software to the public domain# worldwide. This software is distributed without any warranty.## You should have received a copy of the CC0 Public Domain Dedication along with# this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>. # Tests my intuition about references to ADTs, creating references and# modifying them. implement AdtTest; include "sys.m";include "draw.m"; AdtTest: module{    init: fn(ctxt: ref Draw->Context, args: list of string);}; Greeting: adt{    words: string;}; init(ctxt: ref Draw->Context, args: list of string){    sys := load Sys Sys->PATH;     # Create a new instance and take a reference to (a copy of) it.    a := ref Greeting("Hello");    sys->print("Original greeting: %s\n", a.words);     update_greeting(a);        sys->print("Updated greeting: %s\n", a.words);     b := Greeting("Hiya");    c := ref b;    sys->print("New ref c: %x %s\n", c, c.words);    d := ref b;    sys->print("New ref d: %x %s\n", d, d.words);     update_greeting(c);    update_greeting(d);        sys->print("Updated greeting c: %s\n", c.words);    sys->print("Updated greeting d: %s\n", d.words);} update_greeting(b: ref Greeting){    b.words += " Hi!";}