From Matthias Neeracher:
MacPerl is an adaptation of Perl 5.0 for the Macintosh. Perl is an interpreted language optimized for scanning arbitrary text files, extracting information from those text files, and printing reports based on that information. In the words of its author, Larry Wall, Perl is a language for "getting your job done." Perl is often used for system administration, CGI scripts, data transformations, genetic sequence analysis, and more. MacPerl offers almost all the features of Perl, plus loads of Macintosh-specific functions. MacPerl can be used as an application under the Finder or as a tool under MPW.