Programming Perl: The Ultimate Beginner's Guide to Learn Perl Programming Step by Step by John Bach

Author:John Bach [Bach, John]
Language: eng
Format: azw3
Published: 2020-07-13T16:00:00+00:00

sub half (Int $ number) {

return $ number / 2

}

say half 84; # -> 42

If this function is called with a text string, we get the following error:

> say half "Douglas Adams"

=== SORRY! = == Error while compiling <unknown file>

Calling half (Str) will never work with declared signature (Int $ number)

at <unknown file>: 1

------> say <HERE> half "Douglas Adams"

The Int type included in the function signature is a type constraint that can help prevent subtle errors. In some cases, they can also be a nuisance. Consider the code snippet:

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