# does what you think:
print Math::Light::Expression->new("2*3")->val(); 

# force the statement delimiter to be ';'.
# otherwise it's optional, and whitespaces 
# delimit expressions
my $m = Math::Light::Expression->new({force_semicolon => 1});

$m->parse("a = 2; a^(a+b)")->val({ b => 3});

# arguments to val() overwrite variables in statements:
$m->parse("a=1; a*2")->val({ a => -1 }); # result: -2