17.4 Version Numbers🔗ℹ

A valid version string following Racket conventions has one of the following forms:

• ‹maj›.‹min›

• ‹maj›.‹min›.‹sub›

• ‹maj›.‹min›.‹sub›.‹rel›

subject to the following constraints:

• ‹maj›, ‹min›, ‹sub›, and ‹rel› are all canonical decimal representations of Nats (i.e., decimal digits with no leading 0 unless exactly 0);

• ‹rel› is not 0;

• ‹sub› is not 0 unless ‹rel› is included;

• ‹min› has no more than two digits;

• ‹sub› and ‹rel› have no more than three digits.

The constraints force version numbers to be in a canonical form. For example, a would-be version string "4.3.0" must be written instead as "4.3", "4.3.1.0" must be written instead as "4.3.1", and rhombus("4") must be written as "4.0".