[Purdue-pm] Perl 6 feed operator

[Mark Senn]

Purdue Perl Mongers.

Below is some Perl 6 code implemented using feed operators and a simple
loop.  I like the loop below better, Perl 6's dir() has a "test"
parameter to automatically grep file names but I don't know how to use
it for complicated tests yet and even if I did I wanted space to
document things line-by-line.

# Read entries from the current directory.
# Ignore entries that start with ".".
# Ignore non-files.
# Ignore non-writable files.
# Originally I had this
#     dir()
#         ==> grep({$_ !~~ /^\./})
#         ==> grep({$_ ~~ :f})
#         ==> grep({$_ ~~ :w})
#         ==> @entry;
# but I like the following better.
my @entry = ();
for dir()                    # dir automatically ignores . and ..
{
    (/^\./)      and  next;  # ignore anything else that starts with a .
    ($_ ~~ :f)   or   next;  # ignore non-files
    ($_ ~~ :w)   or   next;  # ignore non-writiable files
    push @entry, $_;
}

This is for a program called keep.  Typing "keep filename" deletes
all other files in the current directory unless they start with a
. or are non-writable.

-mark