Perl
Perl is an acronym for Practical Extraction and Report Language. The language, which was authored by Larry Wall in 1987, is designed to scan text files, extract information from those files, and print out reports based on the extracted information.
Following its 1987 release, new versions appeared almost yearly, culminating in the 1995 release of a Perl version for the Macintosh computer. Versions also exist for DOS- and Linux-based operating systems. Because of its strong text processing capabilities, Perl has become one of the most popular languages for writing so-called CGI scripts. CGI, or Common Gateway Interface, enables Web servers to react with users in a dynamic and responsive way. Other scripting languages are Python and Eiffel.
Perl is an interpretive language—it executes instructions by translating the instructions into an intermediate form, rather the conversion directly into machine language (called compiling). An interpreted language can be beneficial to the programmer, as it allows the modification and testing of small sections of the program. Another benefit of an interpretive language like Perl is its educational value, because of its interactive capability.
Although optimized for scanning text, Perl can also deal with binary data. Sophisticate pattern matching techniques enable the rapid scanning of large amounts of data. Unlike most Unix utilities, Perl does not arbitrarily limit the size of the data. The amount of data that can be accommodated is limited only by the memory available. Version 5 of Perl represented a nearly complete rewrite of the earlier versions, and included features that enhanced its utility, such as simplified grammar, which allows the user to learn the language progressively as experience builds. Also, the program can resolve local ambiguities, so that rigid programming definition of every character is not required. The overarching theme of Perl is that the language is designed to be useable and efficient, rather than to produce a program that is technically elegant to the programmer.
Perl was conceived as a language designed for change. The latest version contains an extension system that, much like the module system of Linux, allows the continued development of the language without the necessity to change the core language. The user is able to tailor the language to their particular use, while not changing the core that is more global in its use.
The applications for Perl include financial analysis, analysis of population statistics, and, in the biological world, the Human Genome Project. In the latter, Perl enabled sequencing data from various laboratories to be scanned, patterns recognized, and a cohesive entire sequence assembled.
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