I don't know what it is, but there must be something like this, since
guile has apropos. Try (apropos "close") for example. It will even
tell you what module the procedure is defined in. Delving into the
implementation may be enlightening. OTOH I think this may reveal only
the names of all bound variables rather than all interned symbols.
> Are there too many interned symbols to make this useful (w/o especially
> long prefixes)? Do module namespaces throw a monkey-wrench in this
> (I'm not sure how the symbol hash table(s) are organized).
>
They do, but it's a somewhat solved problem (see above).
- Maciej