Why do Perl variables need to start with $, %,@ (sigils)?

Question

Why do Perl variables need to start with different characters (sigils)?

• Scalar variables start with $

• Hashes start with %

Answer 1

Several reasons are explained by Larry Wall et al in "Programming Perl":

Within any given namespace [...] every variable type has its own subnamespace, determined by the funny character. You can, without fear of conflict, use the same name for a scalar variable, an array, or a hash (or, for that matter, a filehandle, a subroutine matter, a label or your pet llama.)

[...]

Like most computer languages, Perl has a list of reserved words that it recognizes as special keywords. However, because variable names always start with a funny character, reserved words don't actually conflict with variable names.