Metafractran is a derivative of Fractran created by User:Challenger5 in which all program files are irrelevant. Rather than being specified by a program file, code is instead determined from that file's metadata; specifically, its location in the filesystem.
- The list of fractions is given by the longest suffix of the list of components of the filepath of the form
<positive integer>:<positive integer>.
- The name of the file must consist of a single positive integer, representing the starting number, followed by an optional file extension.
The file passed to the interpreter must exist, but no restrictions are otherwise made on its contents.