diff options
| -rw-r--r-- | perl6.html.markdown | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/perl6.html.markdown b/perl6.html.markdown index 6cacc672..f804ef86 100644 --- a/perl6.html.markdown +++ b/perl6.html.markdown @@ -213,11 +213,18 @@ say "Quite truthy" if True; # - Ternary conditional, "?? !!" (like `x ? y : z` in some other languages) my $a = $condition ?? $value-if-true !! $value-if-false; -# - `given`-`when` looks like other languages `switch`, but it's much more powerful thanks to smart matching. -# given just puts its argument into `$_` (like a block), +# - `given`-`when` looks like other languages `switch`, but it's much more powerful thanks to smart matching, +# and thanks to Perl 6's "topic variable", $_. +# This variable contains the default argument of a block, +# a loop's current iteration (unless explicitly named), etc. +# Given simply puts its argument into `$_` (like a block would do), # and `when` uses it using the "smart matching" operator. +# Since other Perl 6 constructs use this variable (as said before, like `for`, blocks, etc), +# this means the powerful `when` is not only applicable along with a `given`, +# but instead anywhere a `$_` exists. given "foo bar" { when /foo/ { # you'll read about the smart-matching operator below -- just know `when` uses it + # this is equivalent to `if $_ ~~ /foo/` say "Yay !"; } when $_.chars > 50 { # smart matching anything with True (`$a ~~ True`) is True, @@ -248,9 +255,14 @@ for @array -> $variable { say "I've found $variable !"; } -# default variable is $_ (like a block) +# As we saw with given, for's default "current iteration" variable is `$_`. +# That means you can use `when` in a `for` just like you were in a when. for @array { say "I've got $_"; + + .say; # This is also allowed. + # A dot call with no "topic" (receiver) is sent to `$_` by default + $_.say; # the above and this are equivalent. } for @array { |