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Moar operators
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@ -78,11 +78,12 @@ unless False {
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say "It's not false !";
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}
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# if (true) say; # Won't work
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# `given`-`when` looks like other languages `switch`, but it's much more powerful thanks to smart matching :
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given "foo bar" { # given just puts its argument into `$_`, and `when` uses it.
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when /foo/ { # smart matching a string with a regex returns true if it matches
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given "foo bar" { # given just puts its argument into `$_`, and `when` uses it using the "smart matching" operator.
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when /foo/ { # you'll read about the smart-matching operator below
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say "Yay !";
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}
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when $_.chars > 50 { # smart matching anything with True gives True, so you can also put "normal" conditionals
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@ -118,4 +119,85 @@ for array {
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if long-computation() -> $result {
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say "The result is $result";
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}
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# Operators
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## Since Perl languages are very much operator-based languages
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## Perl 6 operators are actually just funny-looking subroutines, in syntactic categories,
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## like infix:<+> (addition) or prefix:<!> (bool not)
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## The categories are :
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### - "prefix" : before (like `!` in `!True`).
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### "postfix" : after (like `++` in `$a++`).
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### "infix" : in between (like `*` in `4 * 3`).
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### "circumfix" : around (like `[`-`]` in `[1, 2]`).
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### "post-circumfix" : around, after another term (like `{`-`}` in `%hash{'key'}`)
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## The precedence list can be found here : http://perlcabal.org/syn/S03.html#Operator_precedence
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## But first, we need a little explanation about associativity :
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### Binary operators:
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$a ! $b ! $c; # with a left-associative `!`, this is `($a ! $b) ! $c`
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$a ! $b ! $c; # with a right-associative `!`, this is `$a ! ($b ! $c)`
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$a ! $b ! $c; # with a non-associative `!`, this is illegal
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$a ! $b ! $c; # with a chain-associative `!`, this is `($a ! $b) and ($b ! $c)`
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$a ! $b ! $c; # with a list-associative `!`, this is `infix:<>`
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### Unary operators:
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!$a! # with left-associative `!`, this is `(!$a)!`
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!$a! # with right-associative `!`, this is `!($a!)`
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!$a! # with non-associative `!`, this is illegal
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## Alright, you're set to go !
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## * Equality Checking
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### - `==` is numeric comparison
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3 == 4; # False
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3 != 4; # True
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### - `eq` is string comparison
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'a' eq 'b';
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'a' ne 'b'; # not equal
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'a' !eq 'b'; # same as above
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### - `eqv` is canonical equivalence
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(1, 2) eqv (1, 3);
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### - `~~` is smart matching
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### for a complete combinations list, use this table : http://perlcabal.org/syn/S03.html#Smart_matching
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'a' ~~ /a/; # true if matches regexp
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'key' ~~ %hash; # true if key exists in hash
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$arg ~~ &bool-returning-function; # true if the function, passed `$arg` as an argument, returns True
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1 ~~ Int; # "is of type"
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### - `===` is value identity and uses `.WHICH` on the objects to compare them
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### - `=:=` is container identity and uses `VAR()` on the objects to compare them
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### You also, of course, have `<`, `<=`, `>`, `>=`.
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### Their string equivalent are also avaiable : `lt`, `le`, `gt`, `ge`.
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3 > 4;
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## * Sort comparison
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### They return one value of the `Order` enum : `Less`, `Same` and `More` (which numerify to -1, 0 or +1).
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1 <=> 4; # sort comparison for numerics
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'a' leg 'b'; # sort comparison for string
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$obj eqv $obj2; # sort comparison using eqv semantics
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## * Generic ordering
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3 before 4; # True
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'b' after 'a'; # True
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## * Range constructors
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3 .. 7; # 3 to 7, both included
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### `^` on either side them exclusive on that side :
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3 ^..^ 7; # 3 to 7, not included (basically `4 .. 6`)
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# * And, Or
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## Short-circuit (and tight)
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$a && $b && $c; # returns the first argument that evaluates to False, or the last argument
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$a || $b;
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```
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