Completion for Fish shell for `guile` command

Hi! I wonder to implement a perfect completion for guile. However, I have no idea how for instance to extract all functions defined in a file for -e option. What I had come up with were regular expressions (working just for Scheme code currently). Although I am not sure whether it’s a good solution because there are other languages beside Scheme are supported as it seems (--language={{value}} option). Is there a universal way to get all the possible functions?