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Move stuff around. ventica++

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Nami-Doc 2014-07-25 11:30:50 +02:00
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@ -226,6 +226,58 @@ sub mod() is rw { $x }
mod() = 52; # in this case, the parentheses are mandatory
say $x; #=> 52
# The last expression of a sub is returned automatically (though you may use the `return` keyword, of course):
sub next-index($n) {
$n + 1;
}
my $new-n = next-index(3); # $new-n is now 4
# This is true for everything, except for the looping constructs (due to performance reasons):
# there's no purpose in building a list if we're just going to discard all the results.
# If you still want to build one, you can use the `do` prefix: (or the `gather` prefix, which we'll see later)
sub list-of($n) {
do for ^$n { # note the use of the range-to prefix operator `^` (`0..^N`)
$_ # current loop iteration
}
}
my @list3 = list-of(3); #=> (0, 1, 2)
# We can, for example, add 3 to each value of an array using map :
my @arrayplus3 = map({ $_ + 3 }, @array); # $_ is the implicit argument (the same as for `given` and `for`)
# a sub (`sub {}`) has different semantics than a block (`{}` or `-> {}`) :
# a block doesn't have a function context (though it can have arguments), which means that if you
# return from it, you're going to return from the parent function, compare:
sub is-in(@array, $elem) {
# this will `return` out of `is-in` sub
# once the condition evaluated to True, the loop won't be run anymore
map({ return True if $_ == $elem }, @array);
}
sub truthy-array(@array) {
# this will produce an array of `True` and `False` :
# (you can also say `anon sub` for "anonymous subroutine")
map(sub { if $_ { return True } else { return False } }, @array); # returns the correct value, even in a `if`
}
# `-> {}` and `{}` are pretty much the same thing, except that the former can take arguments,
# and that the latter can be mistaken as a hash by the compiler
# You can also use the "whatever star" to create an anonymous function
# (it'll stop at the furthest operator in the current expression)
my @arrayplus3 = map(*+3, @array); # `*+3` is the same as `{ $_ + 3 }`
my @arrayplus3 = map(*+*+3, @array); # also works. Same as `-> $a, $b { $a + $b + 3 }`
say (*/2)(4); #=> 2
# Immediatly execute the function Whatever created.
say ((*+3)/5)(5); #=> 1.6
# works even in parens !
# but if you need to have more than one argument (`$_`) in a block (without wanting to resort to `-> {}`),
# you can also use the implicit argument syntax, `$^` :
map({ $^a + $^b + 3 }, @array); # same as the above
# Note : those are sorted lexicographically. `{ $^b / $^a }` is like `-> $a, b { $ b / $a }`
### Control Flow Structures
# You don't need to put parenthesis around the condition, but that also means you always have to use brackets (`{ }`) for their body :
@ -428,54 +480,6 @@ multi with-or-without-you {
# (commented because running this would probably lead to some surprising side-effects !)
# ----
# The last expression of a sub is returned automatically (though you may use the `return` keyword, of course):
sub next-index($n) {
$n + 1;
}
my $new-n = next-index(3); # $new-n is now 4
# This is true for everything, except for the looping constructs (due to performance reasons):
# there's no purpose in building a list if we're just going to discard all the results.
# If you still want to build one, you can use the `do` prefix: (or the `gather` prefix, which we'll see later)
sub list-of($n) {
do for ^$n { # note the use of the range-to prefix operator `^` (`0..^N`)
$_ # current loop iteration
}
}
my @list3 = list-of(3); #=> (0, 1, 2)
# We can, for example, add 3 to each value of an array using map :
my @arrayplus3 = map({ $_ + 3 }, @array); # $_ is the implicit argument (the same as for `given` and `for`)
# a sub (`sub {}`) has different semantics than a block (`{}` or `-> {}`) :
# a block doesn't have a function context (though it can have arguments), which means that if you
# return from it, you're going to return from the parent function, compare:
sub is-in(@array, $elem) {
# this will `return` out of `is-in` sub
# once the condition evaluated to True, the loop won't be run anymore
map({ return True if $_ == $elem }, @array);
}
sub truthy-array(@array) {
# this will produce an array of `True` and `False` :
# (you can also say `anon sub` for "anonymous subroutine")
map(sub { if $_ { return True } else { return False } }, @array); # returns the correct value, even in a `if`
}
# `-> {}` and `{}` are pretty much the same thing, except that the former can take arguments,
# and that the latter can be mistaken as a hash by the compiler
# You can also use the "whatever star" to create an anonymous function
# (it'll stop at the furthest operator in the current expression)
my @arrayplus3 = map(*+3, @array); # `*+3` is the same as `{ $_ + 3 }`
my @arrayplus3 = map(*+*+3, @array); # also works. Same as `-> $a, $b { $a + $b + 3 }`
say ((*+3)/5)(5); # immediatly execute the function Whatever created -- works even in parens !
# but if you need to have more than one argument (`$_`) in a block (without wanting to resort to `-> {}`),
# you can also use the implicit argument syntax, `$^` :
map({ $^a + $^b + 3 }, @array); # same as the above
# Note : those are sorted lexicographically. `{ $^b / $^a }` is like `-> $a, b { $ b / $a }`
### Scoping
# In Perl 6, contrarily to many scripting languages (Python, Ruby, PHP, for example),
# you are to declare your variables before using them. You already saw it, with `my`.