πŸ“˜ Universal comparison operators before and after in Perl 6

before and after are the comparison operators, which work with operands of different types. It returns a Boolean value of either True or False depending on which operand was considered to be ordered earlier or later. Type coercion is similar to how it happens with the cmp operator.Β  Remember that depending on the data types … Continue reading “πŸ“˜ Universal comparison operators before and after in Perl 6”

πŸ“˜ Smartmatch operator ~~ in Perl 6

~~ is the smartmatch operator. It compares the objects and tries to work correctly with the operands of any type (that is why the operator is called smart). say 42 ~~ 42.0; # True say 42 ~~ “42”; # True The result of the smartmatching depends on the operand order. Consider the following: say “42.0” … Continue reading “πŸ“˜ Smartmatch operator ~~ in Perl 6”

πŸ“˜ Junction operators |, &, and ^ in Perl 6

|, &, and ^ create the so-called junctions (formerly known in Perl 6 as quantum superpositions). These objects can be used where a scalar is used but behave differently; unlike the scalars, the junctions have multiple values at the same moment in time. The |, &, and ^ operators create, respectively, the junctions of the … Continue reading “πŸ“˜ Junction operators |, &, and ^ in Perl 6”

πŸ“˜ Invocant call operator : in Perl 6

: marks the left side of it as an invocant to call a method on, when a method of an object is used. It is easier to understand how it works in the following example. class C { Β Β Β  method meth($x) { Β Β Β Β Β Β Β  say “meth($x)”; Β Β Β  } } my $o = C.new; meth($o: 42); # … Continue reading “πŸ“˜ Invocant call operator : in Perl 6”

πŸ“˜ Default values in Perl 6 subs

Perl 6 also allows specifying the default values of the sub’s arguments. Syntactically, this looks like an assignment. sub i-live-in(Str $city = “Moscow”) {Β Β  Β Β Β  say “I live in $city.”;Β Β Β Β Β Β Β Β Β Β Β Β  } i-live-in(‘Saint Petersburg’); i-live-in(); # The default city It is also possible to pass values that are not known at the compile phase. When the … Continue reading “πŸ“˜ Default values in Perl 6 subs”

πŸ“˜ Universal comparison operator cmp in Perl 6

There are a few operators, which can compare both strings and numbers, or even compound objects like pairs. cmp compares two objects and returns a value of the Order type, either Less, or Same, or More. say 2 cmp 2;Β Β  # Same say 2 cmp 2.0; # Same say 1 cmp 2;Β Β  # Less say … Continue reading “πŸ“˜ Universal comparison operator cmp in Perl 6”

πŸ“˜ Universal comparison operator eqv in Perl 6

eqv is an operator that tests the two operands for equivalence. It returns the True value if the operands are of the same type and contain the same values. my $x = 3; my $y = 3; say $x eqv $y; # True An example with a bit more complex data structures: my @a = … Continue reading “πŸ“˜ Universal comparison operator eqv in Perl 6”

πŸ“˜ Cross-product operator X in Perl 6

X is the cross product operator, which converts the two given lists to a third one containing all the possible combinations of the elements from the original lists. @c = @a X @b; This is the same as the following sequence: @c = ((@a[0], @b[0]), (@a[0], @b[1]), (@a[0], @b[2]), … (@a[N], @b[0]), (@a[N], @b[1]), … … Continue reading “πŸ“˜ Cross-product operator X in Perl 6”

πŸ“˜ Subroutines, or subs in Perl 6

For a sub, which takes no arguments, its definition and the call are very straightforward and easy. sub call-me { Β Β Β  say “I’m called” } call-me; The syntax for declaring a sub’s parameters is similar to what other languages (including Perl 5.20 and higher) provide. sub cube($x) { Β Β Β  return $x ** 3; } say … Continue reading “πŸ“˜ Subroutines, or subs in Perl 6”

πŸ“˜ Anonymous code blocks in Perl 6

Perl 6 introduces the concept of so-called pointy blocks (or pointy arrow blocks). These are anonymous closure blocks, which return a reference to the function and can take arguments. The syntax of defining pointy blocks is an arrow -> followed by the argument list and a block of code. my $cube = -> $x {$x … Continue reading “πŸ“˜ Anonymous code blocks in Perl 6”

πŸ“˜ Shortcut operator && in Perl 6

&& returns the first of the operands, which, after being converted to a Boolean value, becomes False. If none are False, then the last element is returned. Please note that the result is not a Boolean value but the value of one of the operands (unless they are Boolean already). say 10 && 0; # … Continue reading “πŸ“˜ Shortcut operator && in Perl 6”

πŸ“˜ Shortcut operator ^^ in Perl 6

^^ returns an operand that is True in a Boolean context and that is, at the same time, the only one in the given list. If nothing is found, Nil is returned. As soon as the operator sees the second True value, it stops evaluating the rest, because the result is already known. say 0 … Continue reading “πŸ“˜ Shortcut operator ^^ in Perl 6”