my $result = reduce { print "eval: $a + $b\n"; 
                      eval "$a + $b" }
             1 .. 4;
print "result=$result\n\n";
 
# eval: 1 + 2
# eval:  + 3
# eval:  + 4
# result=4


$result = reduce { print "eval: return $a + $b\n";
                   eval "return $a + $b" }
          1 .. 4;
print "result=$result\n\n";

# eval: return 1 + 2
# eval: return 4 + 3
# eval: return 4 + 4
# result=4