Category: Chapter 1. Perl 6 Essentials

Due to the mechanism of introspection, it is easily possible to tell the type of the data living in a variable (a variable in Perl 6 is often referred as a container). To do that, call the predefined WHAT method on a variable. Even if it is a bare scalar, Perl 6 treats it internally … Continue reading “📘 Variables in Perl 6: Introspection”

The Int type is intended to host integer variables of arbitrary size. For example, no digit is lost in the following assignment: my Int $x =     12389147319583948275874801735817503285431532; say $x; A special syntax exists for defining integers with an other-than-10 base: say :16<D0CF11E0> Also, it is allowable to use the underscore character to separate digits … Continue reading “📘 Int type in Perl 6”

The $_ variable is the one similar to that in Perl 5, which is the default variable containing the current context argument in some cases. Like any other variable, the $_ is an object in Perl 6, even in the simplest use cases. For example, the recent example .say for @*ARGS implicitly contains the $_.say … Continue reading “📘 Frequently used special variables in Perl 6”

The Perl 6 compiler can either read a programme from a file or from the content of the -e command line switch. The simplest “Hello, World!” programme looks like this: say “Hello, Perl 6!”; Save it in a file and run: $ perl6 hello.pl Hello, Perl 6! Alternatively, you may use the -e option: $ … Continue reading “📘 Hello, World! in Perl 6”

The Array variables (i.e., all the variables starting with the @ sigil) are equipped with a couple of simple but rather useful methods. my @a = 1, 2, 3, 5, 7, 11; say @a.Int; # array length say @a.Str; # space-separated values If you print an array, you get its value as a space-separated list … Continue reading “📘 Array in Perl 6”

Perl 6 allows using typed variables. To tell the compiler that the variable is typed, you simply need to name the type while declaring the variable. Some of the types available in Perl 6 are obvious and do not need comments: Bool, Int, Str Array, Hash, Complex Some might require a small comment: Num, Pair, … Continue reading “📘 Built-in types in Perl 6”

In Perl 6, a variable name may be preceded by either a single-character sigil, such as $, @ or %, or with a double character sequence. In the latter case, this is called a twigil. The first character of it means the same thing that a bare sigil does, while the second one extends the … Continue reading “📘 Variables in Perl 6: Twigils”

Perl 6 uses sigils to mark variables. The sigils are partially compatible with the Perl 5 syntax. For instance, scalars, lists and hashes use, respectively, the $, @, and % sigils. my $scalar = 42; say $scalar; It’s not a surprise that the code prints 42. Consider the following fragment, which also gives a predictable … Continue reading “📘 Variables in Perl 6: Sigils”

The usage of the Bool variables is straightforward although there are some details about which you might want to know. The Bool type is a built-in enumeration and provides two values: True and False (or, in a full form, Bool::True and Bool::False). It is permissible to increment or decrement the Boolean variables: my $b = … Continue reading “📘 Bool in Perl 6”

Str is no doubt a string. In Perl 6, there are methods to manipulate strings. Again, you call them as methods on objects. my $str = “My string”; say $str.lc; # my string say $str.uc; # MY STRING say $str.index(‘t’); # 4 Let us now get the length of a string. The naïve attempt to … Continue reading “📘 Str type in Perl 6”

Hashes provide a few methods with clear semantics, for instance: my %hash = Language => ‘Perl’, Version => 6; say %hash.elems;  # number of pairs in the hash say %hash.keys;   # the list of the keys say %hash.values; # the list of the values Here’s the output:  2 (Version Language) (6 Perl) It is possible … Continue reading “📘 Hash in Perl 6”

This is how you declare a typed variable: my Int $x; Here, a scalar container $x may only hold an integer value. Attempts to assign it a value that is not an integer leads to an error: my Int $x; $x = “abc”; # Error: Type check failed in assignment to ‘$x’;             # expected … Continue reading “📘 Typed variables in Perl 6”