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-rw-r--r--perl6.html.markdown31
1 files changed, 18 insertions, 13 deletions
diff --git a/perl6.html.markdown b/perl6.html.markdown
index 45b15f05..1829f964 100644
--- a/perl6.html.markdown
+++ b/perl6.html.markdown
@@ -1,10 +1,9 @@
---
-name: perl6
category: language
language: perl6
filename: learnperl6.pl
contributors:
- - ["Nami-Doc", "http://github.com/Nami-Doc"]
+ - ["vendethiel", "http://github.com/vendethiel"]
---
Perl 6 is a highly capable, feature-rich programming language made for at
@@ -374,6 +373,8 @@ say @array[^10]; # you can pass arrays as subscripts and it'll return
say join(' ', @array[15..*]); #=> 15 16 17 18 19
# which is equivalent to:
say join(' ', @array[-> $n { 15..$n }]);
+# Note: if you try to do either of those with an infinite array,
+# you'll trigger an infinite loop (your program won't finish)
# You can use that in most places you'd expect, even assigning to an array
my @numbers = ^20;
@@ -735,7 +736,7 @@ try {
# You can throw an exception using `die`:
die X::AdHoc.new(payload => 'Error !');
-# You can access the last exception with `$!` (usually used in a `CATCH` block)
+# You can access the last exception with `$!` (use `$_` in a `CATCH` block)
# There are also some subtelties to exceptions. Some Perl 6 subs return a `Failure`,
# which is a kind of "unthrown exception". They're not thrown until you tried to look
@@ -763,8 +764,9 @@ try {
# and `enum`) are actually packages. (Packages are the lowest common denominator)
# Packages are important - especially as Perl is well-known for CPAN,
# the Comprehensive Perl Archive Network.
-# You usually don't use packages directly: you use `class Package::Name::Here;`,
-# or if you only want to export variables/subs, you can use `module`:
+# You're not supposed to use the package keyword, usually:
+# you use `class Package::Name::Here;` to declare a class,
+# or if you only want to export variables/subs, you can use `module`:
module Hello::World { # Bracketed form
# If `Hello` doesn't exist yet, it'll just be a "stub",
# that can be redeclared as something else later.
@@ -774,11 +776,6 @@ unit module Parse::Text; # file-scoped form
grammar Parse::Text::Grammar { # A grammar is a package, which you could `use`
}
-# NOTE for Perl 5 users: even though the `package` keyword exists,
-# the braceless form is invalid (to catch a "perl5ism"). This will error out:
-# package Foo; # because Perl 6 will think the entire file is Perl 5
-# Just use `module` or the brace version of `package`.
-
# You can use a module (bring its declarations into scope) with `use`
use JSON::Tiny; # if you installed Rakudo* or Panda, you'll have this module
say from-json('[1]').perl; #=> [1]
@@ -870,8 +867,16 @@ LEAVE { say "Runs everytime you leave a block, even when an exception
PRE { say "Asserts a precondition at every block entry,
before ENTER (especially useful for loops)" }
+# exemple:
+for 0..2 {
+ PRE { $_ > 1 } # This is going to blow up with "Precondition failed"
+}
+
POST { say "Asserts a postcondition at every block exit,
after LEAVE (especially useful for loops)" }
+for 0..2 {
+ POST { $_ < 2 } # This is going to blow up with "Postcondition failed"
+}
## * Block/exceptions phasers
sub {
@@ -1239,14 +1244,14 @@ so 'foo!' ~~ / <-[ a..z ] + [ f o ]> + /; # True (the + doesn't replace the left
# Group: you can group parts of your regexp with `[]`.
# These groups are *not* captured (like PCRE's `(?:)`).
so 'abc' ~~ / a [ b ] c /; # `True`. The grouping does pretty much nothing
-so 'fooABCABCbar' ~~ / foo [ A B C ] + bar /;
+so 'foo012012bar' ~~ / foo [ '01' <[0..9]> ] + bar /;
# The previous line returns `True`.
-# We match the "ABC" 1 or more time (the `+` was applied to the group).
+# We match the "012" 1 or more time (the `+` was applied to the group).
# But this does not go far enough, because we can't actually get back what
# we matched.
# Capture: We can actually *capture* the results of the regexp, using parentheses.
-so 'fooABCABCbar' ~~ / foo ( A B C ) + bar /; # `True`. (using `so` here, `$/` below)
+so 'fooABCABCbar' ~~ / foo ( 'A' <[A..Z]> 'C' ) + bar /; # `True`. (using `so` here, `$/` below)
# So, starting with the grouping explanations.
# As we said before, our `Match` object is available as `$/`: