Why must 'if' clause in Perl come with either curly brackets or nothing?

Question

This is ok:

if ($some_var==$some_value) {}

This is ok too:

print "hello" if ($some_var==$some_value);

But this raises an error:

if ($some_var==$some_value) print "some_message";

Why must 'if' clause in Perl come with either curly brackets or nothing?

Answer 1

To avoid the well-known problem in compiler construction known as a "dangling else". See http://en.wikipedia.org/wiki/Dangling_else

Answer 2

Perl has a rather complex syntax and is rather difficult to parse. I gather that curly brackets were made mandatory following an if clause so as to remove an ambiguity and make Perl code easier to parse.