Perl 6 Deep Dive

Lazy readers

The IO::Handle class defines a few methods for lazy reading. The laziness here means that Perl 6 should perform actual reading when the program really needs another portion of data. So it should not read the whole file immediately.

The lines method returns a list of lines. Here is an example of a short program that copies its input to the output:

.say for lines;

This can be re-written in a different form with a more traditional syntax:

for $*IN.lines -> $line {
    say $line;
}

The call of $*IN.lines returns an array of the lines from input. We can directly save it in a variable, for example, and use it for printing:

my @lines = $*IN.lines;
.say for @lines;

An important thing is that the lines method removes the new line characters ...