Much has been said about designing good user interface, whether for desktop applications, websites or games. There are whole books available about GUI design and even this year's IGK-7'2010 conference featured two lectures about the interface in games. But what about interfaces for programmers?
I can't find much about the rules of good library API design and I believe there is much to say in this subject. I only know The Little Manual of API Design written by Jasmin Blanchette from Trolltech/Nokia, one of the creators of Qt library (thanks for the link Przemek!). There is also a blog entry about Math Library, which is quite interesting. Inspired by it, I've came up with a general thought that you cannot have all the following features when designing a library and its API, you have to choose 2 or 3 of them and make some compromise:
I think some patterns and best practices as well as some anti-patterns could be found when you look at interfaces of many libraries. Maybe I'll post some more of my thoughts on this subject in the future. In the meantime, do you know any other resources about API design?