@screwlisp
This is Obviously The Right Thing To Do (tm) and no doubt famous in the Chibi Scheme world, but I don't know if it's known elsewhere nor how many equivalent things (*intelligent* completion) are available for other dialects / other languages:

> Scheme-complete provides a single function, scheme-smart-complete, which you can use for intelligent, context-sensitive completion for any Scheme implementation. The intelligent completion comes from the use of simple type inference.
https://github.com/ashinn/scheme-complete

@aartaka