DOCUMENT();

loadMacros(
"PGstandard.pl",
"PGML.pl",
"contextArbitraryString.pl",
);
TEXT(beginproblem());

# https://webwork.maa.org/moodle/mod/forum/discuss.php?d=2950

Context("Numeric");
Context()->strings->add(
alpha => {caseSensitive => 1},
beta  => {caseSensitive => 1},
gamma  => {caseSensitive => 1},
delta  => {caseSensitive => 1},
);
Context()->parens->set("{" => {type => "List", removable => 0});

$answer1 = Compute("{alpha,beta,gamma}");

$answer2 = Compute("{alpha,beta}, {gamma,delta}");

BEGIN_PGML
# Answer is a set of strings or several sets of strings

Using set notation, what is the set of the first three letters of the Greek alphabet in their natural order? [__________________]{$answer1->cmp(list_type=>"set", removeParens=>0, implicitList=>0, showParenHints=>1, ordered=>1)}  Note: [| {beta, alpha, gamma} |] is marked incorrect (as expected).

Enter [| {alpha,beta}, {gamma,delta} |] [_____________________]{$answer2->cmp(list_type=>"set", removeParens=>0, implicitList=>0, showParenHints=>1)}  Note: [| {gamma,delta}, {alpha,beta} |] is marked correct, but [| {delta,gamma}, {alpha,beta} |] is not marked correct (not as expected).

END_PGML

ENDDOCUMENT();