Problem Statement

In bioinformatics, long character strings are often encoded in a format called FASTA.
A FASTA file can contain several strings, each identified by a name marked by a > (greater than) character at the beginning of the line.

Write a program that reads a FASTA file such as: Note that a high-quality implementation will not hold the entire file in memory at once; real FASTA files can be multiple gigabytes in size.

Let's start with the solution:

my $fasta_example = <<'END_FASTA_EXAMPLE';
>Rosetta_Example_1
THERECANBENOSPACE
>Rosetta_Example_2
THERECANBESEVERAL
LINESBUTTHEYALLMUST
BECONCATENATED
END_FASTA_EXAMPLE

my $num_newlines = 0;
while ( < $fasta_example > ) {
	if (/\A\>(.*)/) {
		print "\n" x $num_newlines, $1, ': ';
	}
	else {
		$num_newlines = 1;
		print;
	}
}