perl6的小技巧杂记（持续更新ing）

1、读文件

#001一次读入全部内容
my $string = slurp 'sample.txt';
say $string;

#002按行读入文件内容
for open('sample.txt').lines
{
   .say;
 }

#003按行读入文件内容
my @content = lines ('sample.txt');
say @content.join("\n");

2、写文件

my $fh =open "sample.txt",:a;
$fh.print('foo');
$fh.say('bar');
$fh.close;
say slurp('sample.txt')

3、printf、format

say '100.125'.fmt('%.2f');
printf '%.2f','100.125';

4、like #List::Util qw(reduce ) in the perl5

my @ary = 1,2,3,4,5;
say 'Sum: ', [+] @ary;
say 'Product: ', [*] @ary;

5、（2、4、6、8）

for [2, *+2 ... 8] ->$x{
    say $x;
}
say [2, *+2 ... 8];

6、字符类型

my $x; say $x.WHAT; # Any()
my Int $y; say $y.WHAT; # Int()
my Str $z; say $z.WHAT; # Str()

7、like my $str =<> in the perl5

my $str = prompt("Enter a string: ");

8、绑定

my $x = 'foo';
#like {my $y=\$x} in perl5
my $y := $x;
$y = 'bar';
say $x; # 'bar'

9、上下文

my @array = 1, 2, 3;
# generic item context
my $a = @array; say $a.WHAT; # prints Array
# string context
say ~@array; # "1 2 3"
# numeric context
say +@array; # 3
# boolean context
my $is-nonempty = ?@array; say $is-nonempty;