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More clarifications. @masak++
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@ -197,6 +197,10 @@ say $x; #=> 52
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## Conditionals
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# - `if`
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# Before talking about `if`, we need to know which values are "Truthy" (represent True),
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# and which are "Falsey" (or "Falsy") -- meaning they represent False.
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# Only these values are Falsey: (), 0, "0", Nil, A type, and of course False itself.
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# Every other value is Truthy.
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if True {
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say "It's true !";
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}
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@ -341,7 +345,7 @@ say @array[^10]; # you can pass arrays as subscripts and it'll return an array o
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# so you'll end with an infinite loop.
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## * And, Or
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3 && 4; # True. Calls `.Bool` on `3`
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3 && 4; # 4, which is Truthy. Calls `.Bool` on `4` and gets `True`.
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0 || False; # False. Calls `.Bool` on `0`
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## Short-circuit (and tight) versions of the above
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@ -448,7 +452,7 @@ say ((*+3)/5)(5); #=> 1.6
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# you can also use the implicit argument syntax, `$^` :
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map({ $^a + $^b + 3 }, @array); # same as the above
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# Note : those are sorted lexicographically. `{ $^b / $^a }` is like `-> $a, b { $b / $a }`
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# Note : those are sorted lexicographically. `{ $^b / $^a }` is like `-> $a, $b { $b / $a }`
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## Multiple Dispatch
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# Perl 6 can decide which variant of a `sub` to call based on the type of the arguments,
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@ -813,24 +817,28 @@ sub postfix:<!>(Int $n) {
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[*] 2..$n; # using the reduce meta-operator ... See below ;-) !
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}
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say 5!; #=> 120
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# (postfix is after)
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# Postfix operators (after) have to come *directly* after the term.
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# No whitespace. You can use parentheses to disambiguate, i.e. `(5!)!`
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sub infix:<times>(Int $n, Block $r) { # infix in the middle
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for ^$n {
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$r(); # needs the parentheses because it's a scalar
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$r(); # You need the explicit parentheses to call the function in `$r`,
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# else you'd be referring at the variable itself, kind of like with `&r`.
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}
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}
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3 times -> { say "hello" }; #=> hello
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#=> hello
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#=> hello
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# You're very recommended to put spaces
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# around your infix operator calls.
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# For circumfix and post-circumfix ones
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sub circumfix:<[ ]>(Int $n) {
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$n ** $n
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}
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say [5]; #=> 3125
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# circumfix is around
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# circumfix is around. Again, not whitespace.
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sub postcircumfix:<{ }>(Str $s, Int $idx) { # post-circumfix is "after a term, around something"
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$s.substr($idx, 1);
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@ -915,7 +923,7 @@ for <well met young hero we shall meet later> {
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# (but will still return `False` for "met" itself, due to the leading `^` on `ff`),
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# until it sees "meet", which is when it'll start returning `False`.
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# The difference between `ff` (flip-flop) and `fff` (flip-flop) is that
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# The difference between `ff` (awk-style) and `fff` (sed-style) is that
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# `ff` will test its right side just as its left side changes to `True`,
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# and can get back to `False` right away (*except* it'll be `True` for the iteration that matched)
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# while `fff` will wait for the next iteration to try its right side, once its left side changed:
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@ -935,8 +943,8 @@ for <test start print this stop you stopped printing start printing again stop n
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# you might also use a Whatever Star,
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# which is equivalent to `True` for the left side or `False` for the right:
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for (1, 3, 60, 3, 40, 60) {
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.say if $_ > 50 ff *; # Once the flip-flop reached a number greater than 50, it'll never go back to `False`
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for (1, 3, 60, 3, 40, 60) { # Note: the parenthesis are superfluous here -- sometimes called "superstitious"
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.say if $_ > 50 ff *; # Once the flip-flop reaches a number greater than 50, it'll never go back to `False`
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#=> 60 3 40 60
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}
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