A crate becomes mature when it reaches version 1.0. That milestone means that the following versions 1.x will be compatible with it. Instead, for versions 0.x, there is no such guarantee, and any version can have an application programming interface (API) that's quite different from the previous one.
Having a mature version is important for several reasons, listed as follows:
- When you upgrade your dependency to a newer version of a crate (to use new features of that library), you are guaranteed that your existing code won't get broken—that is, it will continue to behave in a previous way, or in a better way. Without such a guarantee, you typically need to review all your code using that crate and fix all the incompatibilities.
- Your investment in know-how is preserved. You need to neither retrain yourself nor your coworkers and not even update your documentation.
- Typically, software quality is improved. If a version of an API remains unchanged for a long...