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More clarifications. @masak++

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Nami-Doc
2014-07-26 01:11:31 +02:00
parent 61351ee266
commit 8b168d41cc
1 changed files with 16 additions and 8 deletions
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perl6.html.markdown
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@@ -197,6 +197,10 @@ say $x; #=> 52
## Conditionals ## Conditionals
# - `if` # - `if`
# Before talking about `if`, we need to know which values are "Truthy" (represent True),
# and which are "Falsey" (or "Falsy") -- meaning they represent False.
# Only these values are Falsey: (), 0, "0", Nil, A type, and of course False itself.
# Every other value is Truthy.
if True { if True {
say "It's true !"; say "It's true !";
} }
@@ -341,7 +345,7 @@ say @array[^10]; # you can pass arrays as subscripts and it'll return an array o
# so you'll end with an infinite loop. # so you'll end with an infinite loop.
## * And, Or ## * And, Or
3 && 4; # True. Calls `.Bool` on `3` 3 && 4; # 4, which is Truthy. Calls `.Bool` on `4` and gets `True`.
0 || False; # False. Calls `.Bool` on `0` 0 || False; # False. Calls `.Bool` on `0`
## Short-circuit (and tight) versions of the above ## Short-circuit (and tight) versions of the above
@@ -448,7 +452,7 @@ say ((*+3)/5)(5); #=> 1.6
# you can also use the implicit argument syntax, `$^` : # you can also use the implicit argument syntax, `$^` :
map({ $^a + $^b + 3 }, @array); # same as the above map({ $^a + $^b + 3 }, @array); # same as the above
# Note : those are sorted lexicographically. `{ $^b / $^a }` is like `-> $a, b { $b / $a }` # Note : those are sorted lexicographically. `{ $^b / $^a }` is like `-> $a, $b { $b / $a }`
## Multiple Dispatch ## Multiple Dispatch
# Perl 6 can decide which variant of a `sub` to call based on the type of the arguments, # Perl 6 can decide which variant of a `sub` to call based on the type of the arguments,
@@ -813,24 +817,28 @@ sub postfix:<!>(Int $n) {
[*] 2..$n; # using the reduce meta-operator ... See below ;-) ! [*] 2..$n; # using the reduce meta-operator ... See below ;-) !
} }
say 5!; #=> 120 say 5!; #=> 120
# (postfix is after) # Postfix operators (after) have to come *directly* after the term.
# No whitespace. You can use parentheses to disambiguate, i.e. `(5!)!`
sub infix:<times>(Int $n, Block $r) { # infix in the middle sub infix:<times>(Int $n, Block $r) { # infix in the middle
for ^$n { for ^$n {
$r(); # needs the parentheses because it's a scalar $r(); # You need the explicit parentheses to call the function in `$r`,
# else you'd be referring at the variable itself, kind of like with `&r`.
} }
} }
3 times -> { say "hello" }; #=> hello 3 times -> { say "hello" }; #=> hello
#=> hello #=> hello
#=> hello #=> hello
# You're very recommended to put spaces
# around your infix operator calls.
# For circumfix and post-circumfix ones # For circumfix and post-circumfix ones
sub circumfix:<[ ]>(Int $n) { sub circumfix:<[ ]>(Int $n) {
$n ** $n $n ** $n
} }
say [5]; #=> 3125 say [5]; #=> 3125
# circumfix is around # circumfix is around. Again, not whitespace.
sub postcircumfix:<{ }>(Str $s, Int $idx) { # post-circumfix is "after a term, around something" sub postcircumfix:<{ }>(Str $s, Int $idx) { # post-circumfix is "after a term, around something"
$s.substr($idx, 1); $s.substr($idx, 1);
@@ -915,7 +923,7 @@ for <well met young hero we shall meet later> {
# (but will still return `False` for "met" itself, due to the leading `^` on `ff`), # (but will still return `False` for "met" itself, due to the leading `^` on `ff`),
# until it sees "meet", which is when it'll start returning `False`. # until it sees "meet", which is when it'll start returning `False`.
# The difference between `ff` (flip-flop) and `fff` (flip-flop) is that # The difference between `ff` (awk-style) and `fff` (sed-style) is that
# `ff` will test its right side just as its left side changes to `True`, # `ff` will test its right side just as its left side changes to `True`,
# and can get back to `False` right away (*except* it'll be `True` for the iteration that matched) # and can get back to `False` right away (*except* it'll be `True` for the iteration that matched)
# while `fff` will wait for the next iteration to try its right side, once its left side changed: # while `fff` will wait for the next iteration to try its right side, once its left side changed:
@@ -935,8 +943,8 @@ for <test start print this stop you stopped printing start printing again stop n
# you might also use a Whatever Star, # you might also use a Whatever Star,
# which is equivalent to `True` for the left side or `False` for the right: # which is equivalent to `True` for the left side or `False` for the right:
for (1, 3, 60, 3, 40, 60) { for (1, 3, 60, 3, 40, 60) { # Note: the parenthesis are superfluous here -- sometimes called "superstitious"
.say if $_ > 50 ff *; # Once the flip-flop reached a number greater than 50, it'll never go back to `False` .say if $_ > 50 ff *; # Once the flip-flop reaches a number greater than 50, it'll never go back to `False`
#=> 60 3 40 60 #=> 60 3 40 60
} }