diff options
Diffstat (limited to 'perl6.html.markdown')
| -rw-r--r-- | perl6.html.markdown | 38 |
1 files changed, 21 insertions, 17 deletions
diff --git a/perl6.html.markdown b/perl6.html.markdown index 45b15f05..5082a433 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 @@ -104,7 +103,7 @@ sub say-hello-to(Str $name) { # You can provide the type of an argument ## It can also have optional arguments: sub with-optional($arg?) { # the "?" marks the argument optional - say "I might return `(Any)` (Perl's "null"-like value) if I don't have + say "I might return `(Any)` (Perl's 'null'-like value) if I don't have an argument passed, or I'll return my argument"; $arg; } @@ -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 `$_` in a `CATCH` block) # There are also some subtelties to exceptions. Some Perl 6 subs return a `Failure`, # which is a kind of "unthrown exception". They're not thrown until you tried to look @@ -763,8 +764,9 @@ try { # and `enum`) are actually packages. (Packages are the lowest common denominator) # Packages are important - especially as Perl is well-known for CPAN, # the Comprehensive Perl Archive Network. -# You usually don't use packages directly: you use `class Package::Name::Here;`, -# or if you only want to export variables/subs, you can use `module`: +# You're not supposed to use the package keyword, usually: +# you use `class Package::Name::Here;` to declare a class, +# or if you only want to export variables/subs, you can use `module`: module Hello::World { # Bracketed form # If `Hello` doesn't exist yet, it'll just be a "stub", # that can be redeclared as something else later. @@ -774,11 +776,6 @@ unit module Parse::Text; # file-scoped form grammar Parse::Text::Grammar { # A grammar is a package, which you could `use` } -# NOTE for Perl 5 users: even though the `package` keyword exists, -# the braceless form is invalid (to catch a "perl5ism"). This will error out: -# package Foo; # because Perl 6 will think the entire file is Perl 5 -# Just use `module` or the brace version of `package`. - # You can use a module (bring its declarations into scope) with `use` use JSON::Tiny; # if you installed Rakudo* or Panda, you'll have this module say from-json('[1]').perl; #=> [1] @@ -806,9 +803,8 @@ module Foo::Bar { my sub unavailable { # `my sub` is the default say "Can't access me from outside, I'm my !"; } + say ++$n; # increment the package variable and output its value } - - say ++$n; # lexically-scoped variables are still available } say $Foo::Bar::n; #=> 1 Foo::Bar::inc; #=> 2 @@ -870,8 +866,16 @@ 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 { $_ < 2 } # This is going to blow up with "Postcondition failed" +} ## * Block/exceptions phasers sub { @@ -1239,14 +1243,14 @@ so 'foo!' ~~ / <-[ a..z ] + [ f o ]> + /; # True (the + doesn't replace the left # Group: you can group parts of your regexp with `[]`. # These groups are *not* captured (like PCRE's `(?:)`). so 'abc' ~~ / a [ b ] c /; # `True`. The grouping does pretty much nothing -so 'fooABCABCbar' ~~ / foo [ A B C ] + bar /; +so 'foo012012bar' ~~ / foo [ '01' <[0..9]> ] + bar /; # The previous line returns `True`. -# We match the "ABC" 1 or more time (the `+` was applied to the group). +# We match the "012" 1 or more time (the `+` was applied to the group). # But this does not go far enough, because we can't actually get back what # we matched. # Capture: We can actually *capture* the results of the regexp, using parentheses. -so 'fooABCABCbar' ~~ / foo ( A B C ) + bar /; # `True`. (using `so` here, `$/` below) +so 'fooABCABCbar' ~~ / foo ( 'A' <[A..Z]> 'C' ) + bar /; # `True`. (using `so` here, `$/` below) # So, starting with the grouping explanations. # As we said before, our `Match` object is available as `$/`: @@ -1325,7 +1329,7 @@ so 'ayc' ~~ / a [ b | y ] c /; # `True`. Obviously enough ... -### Extra: the MAIN subroutime +### Extra: the MAIN subroutine # The `MAIN` subroutine is called when you run a Perl 6 file directly. # It's very powerful, because Perl 6 actually parses the arguments # and pass them as such to the sub. It also handles named argument (`--foo`) |