@students = (
{
   name  => "Guy",
   college => "Yale",
},
{
   name  => "Gil",
   college => "Harvard",
},
{
   name  => "Gil",
   college => "Harvard",
},
);


##</code><code>##

@uniq_students = (
{
   name  => "Guy",
   college => "Yale",
},
{
   name  => "Gil",
   college => "Harvard",
},
);

##</code><code>##

##Solution for one hash key
my @unique = do { my %seen; grep { !$seen{$_->{name}}++ } @students};