sub MAIN (

    Str :$fasta! where *.IO.f,

    Int :$number=100,

    Str :$out-dir=$*PROGRAM.IO.dirname

) {

    mkdir $out-dir unless $out-dir.IO.d;

    my $ext      = $fasta.IO.extension;

    my $basename = $fasta.IO.basename;

    $basename ~~ s/\.$ext$//;

    sub writer (@seqs) {

        state $fnum = 0;

        my $fname = $*SPEC.catfile(

            $out-dir, sprintf('%s.%04d.%s', $basename, ++$fnum, $ext)

        );

        printf "Writing %s to %s\n", @seqs.elems, $fname.IO…

sub MAIN (:$out-dir="", *@fastq) {

    if ($out-dir.chars > 0 && ! $out-dir.IO.d) {

        mkdir $out-dir;

    }

    my $i = 0;

    for @fastq -> $fastq {

        (my $basename = $fastq.IO.basename) ~~ s/\.\w*?$//;

        my $out-file = $*SPEC.catfile(

            $out-dir || $fastq.IO.dirname, $basename ~ '.fa');

        printf "%3d: %s -> %s\n",

            ++$i, $fastq.IO.basename, $out-file;

        my $out-fh   = open $out-file, :w;

        for $fastq.IO.lines -> $header, $seq, $brea…

I have some FASTA files with headers like this:

>gi|83274083|ref|AC_000032.1| Mus musculus strain mixed chromosome 10, alternate assembly Mm_Celera, whole genome shotgun sequence

I wanted to extract just the 2nd field, so here's a Perl 6 script to do that:

#!/usr/bin/env perl6

use File::Temp;

sub MAIN (*@files) {

    my $i = 0;

    for @files -> $file {

        my ($tmpfile, $tmpfh) = tempfile();

        printf "%3d: %s\n", ++$i, $file.IO.basename;

        for $file.IO.lines -> $line {

            if $line.substr…