Parsing fasta files in perl ruby python and go

append.pl

#!/usr/bin/env perl

use warnings;use strict;

my ($header,$sequence);
$header = <>;
chomp $header;
while(my $line = <>){
  chomp $line;
  if($line =~ /^>/){
    $header = substr($header,1);
    ##########
    #Process Record
    ##########
    $header = $line;
    $sequence = ''
  } else {
    $sequence .= $line;
  }
}
##########
#Process Last Record
##########

fasta.pl

#!/usr/bin/env perl

use warnings;use strict;use English;

local $RS = ">";
my $first = <>;
while(my $record = <>){
  chomp $record;
  my $newline_loc = index($record,"\n");
  my $header = substr($record,0,$newline_loc);
  my $sequence = substr($record,$newline_loc+1);
  $sequence =~ tr/\n//d;
  ##########
  #Process record
  ##########
}

fasta.py

#!/usr/bin/env python

import os,sys$

f = open(sys.argv[1],'r')$
header = f.readline()$
header = header.rstrip(os.linesep)$
sequence=''$
for line in f:$
  line = line.rstrip('\n')$
  if(line[0] == '>'):$
    header = header[1:]$
    ##########$
    #Process Record$
    ##########$
    header = line$
    sequence = ''$
  else:$
    sequence += line$

fasta.rb

#!/usr/bin/env ruby

$/ = ">"$
ARGF.gets$
while rec = ARGF.gets$
  rec.chomp!$
  nl = rec.index("\n")$
  header = rec[0..nl-1]$
  seq = rec[nl+1..-1]$
  seq.gsub!(/\n/,'')$
  ##########
  #Process record
  ##########
end$

fasta_example.fa

>chr1|this is a fasta header|example
CCTAAACCCTGAACCCTAAACCCTAAACCCTGAACCCTAAACCCTGAACCCTGAACCCTAAACCCTGAACCCTAAACCTA
AACCCTGAACCCTGAACCCTAAACCCTGAACCCTAAACCCTAAACCCTAAACCTAAACCCTGAACCCTAAACCTAAACCC
TGAACCCTAAACCCTAAACCCTGAACCCTAAACCTAAACCCTGAACCCTAACCCCTGAACCCTAAACCCTGAACCCTAAA
CCCTGAAACCTGAACCCTGAACCCTAAACCCTAAACCCTGAACCCTAAACCCTGAACCCTGAACCCTAAACCCTGAACCC
>chr2|another record
TAAACCCTGAACCCTAAACCCTAAACCCTGAACCCTAAACCTAAACCATGAACCCTAAACCCTGAACCCTAAACCCTAAA
CCCTGAACCCTAAACCCTGAACCCTAAACCTAAACCCTAAACCCTGAACCCTAAACCTGAACCCTAAACCCCTAAACCTA
AACCCTGAAACCTAAACCCTAAACCCTGAACCCTAAACCCTAAACCCTGAACCCTGAAACCCTGAACCCTAAACCATGAA
CCCTGAACCCTAAACCCTAAACCCTAAACCCTGAACCCTGAACCCTAAACCTAAACCCTGAACCCTGAACCCTAAACCCT
GAACCCTAAACCCTAAACCCTGAACCCTAAACCCTGAACCCTAAACCCTGAACCCTGAACCCTAAACCCTGAACCCTAAA