I need a way to list the names (without the body/content/value) of aliases, functions, variables, arrays in zsh. Optimally it should behave like
compgen -a # will list all the aliases you could run.
compgen -A function # will list all the functions you could run.
compgen -A variable # will list all the variables defined.
I need this to develop env_parallel.zsh: https://www.gnu.org/software/parallel/env_parallel.html