ABSTRACT
How many different classical FORTRAN programs can we write with 7 characters or fewer, not counting blanks? Using the language elements I have covered so far, this is the only one.
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If we let the source text get longer, the number of character combinations that are syntactically legal and semantically meaningful programs increases very quickly. The total grows even faster if we include the FORTRAN statements that I have intentionally omitted until now (listed in the Omissions Section of each Chapter). For source lengths typical of real applications, the number of possible programs in classical FORTRAN is unimaginably huge, though it is dwarfed by the number of legal PL1, C, or Ada programs or, as we shall see in §17.1, by the number of legal FORTRAN-90 programs. Of course, only a tiny fraction of the possible programs in any language do something useful, and only a tiny fraction of those have the desirable attributes listed in §12.1.
