Operator Unary minus- in Perl.
A Unary operation is operation with only one operand.
The Unary arithmetic operators act on a single operand.
Which particular operators exist and whether they are Unary or binary depends on what operators have been
defined by the system or the user.
If the first argument is one of the Unary conditional operators(see section Bash Conditional Expressions),
the expression is true if the Unary test is true.
Process period. We are interested in those kinds of
infinitary objects which somehow have finitary representations. It can be infinite sets represented as predicates like Unary.
In the case if you apply the Unary minus to the line that starts with a plus or minus,
the result is a string that begins with another character. Here's an example:.
If Unary minus is applied to a number or to a string which contains number,
then the operation result is a number with an opposite sign(except for a situation with zero, about it in the next section).