- catamorhisms, category theory
- attribute grammars
are described there. And there are links from that article to other materials providing deep insights in these powerful theories: attribute grammar tools and articles of the Essential Haskell Compiler project.
It is no wonder that it is exactly a compiler project homepage that provides good circular programming and attribute grammar tutorials
the reason may be that a compiler project is complex enough to require good separation of concerns, modularity, reuse (goals of Aspect Oriented Programming, too), and attribute grammars are powerful tools to achieve these goals.
2 Portals or other rich resources
Utrecht University's Attribute Grammar System tools include also an attribute grammar compiler, UUAGC. The concept of attribute grammar was used in their Essential Haskell Compiler project, which gives us not only a working programming language, but also a good didactical material about using attribute grammars, e.g. in writing compilers.
Albeits these materials are self-contained, they reveal that the theory of attribute grammars is related to other concepts (circular programming, catamorphism).