use Data::Dumper;

print Dumper
    map { my $a=$_;
	  map { my $b=$_;
		map { $a**2 == $b **2 + $_ **2
			?  [ $_, $b, $a ]
			:  ()
		} (1..$b)
	    } (1..$a)
	} (1..10);


print Dumper
    grep { $_->[0]**2 == $_->[1] **2 + $_->[2] **2 }
        map { my $a=$_;
	    map { my $b=$_;
		map {
		    [ $a, $b, $_ ]
		} (1..$b)
	    } (1..$a)
	} (1..10);