>>3001 I know very little about this topic, but I have a C++ program I'm working on that I'd like to provide a reduced & simplistic Python API for so users can script the most basic parts. ATM I'm assuming the Boost library for this would be a reasonable choice, though I haven't yet reached the stage where I'll need to do serious investigation and prototyping for it.

Guile's bindings are nice. Even withing C you can do very lispy things with it. It has a problem in which the "context" is implicit and pretty much invisible, so you can't use it as-is but you have to pass a function pointer to a function which initialized the context; when your function is called, you can use Guile's API however you want, until your function terminates. Under normal cirumstances it wouldn't be too much of a hassle, but I'm using it in a program with a lot of asynchronous operations, so I ended up writing a function which is called when the asynchronous task is executed, which calls the function to temporarily intialize the Guile context (for various reasons I can't keep the whole program in Guile mode all the time) so that the Guile API can be used. In the worst case the callback chain can reach more than three functions just to iterate over a list.