What would it take to expose a procedure in the interpreter for completing symbols in the symbol table. What I mean is, I'd like a scheme procedure I could call with a string representing either a full or a partial symbol, and the procedure would give me back a list of the possible completions for currently defined symbols.

Essentially I want a procedure that does what the tab completion in the interpreter's REPL does.

I'm using the partially-implemented swank backend that James Long was working on a while back, and I found these procedures that Marc posted to the list back in March of '09:

(define (symbol-table->list st)

(define (symbol-chain s syms) (let loop ((s s) (syms syms)) (if (symbol? s) (loop (##vector-ref s 2) (cons s syms)) syms)))

(let loop ((lst (vector->list st)) (syms '())) (if (pair? lst) (loop (cdr lst) (symbol-chain (car lst) syms)) (reverse syms))))

(define (interned-symbols) (symbol-table->list (##symbol-table)))

(pp (length (interned-symbols)))

(that was from this post: https://mercure.iro.umontreal.ca/pipermail/gambit-list/2009-March/003308.htm... )

From that I cobbled together a very inefficient hash-table-based tab

completion (especially inefficient because of duplicating the entire symbol table in a hash table, one key per symbol). I realize this is a complete kludge and wastes tremendous amounts of memory. I'd like to do it right and just query the symbol table itself, since the data is obviously already there.

I found the complete_word(), lineeditor_word_completion(), and visit_symbol() functions in os_tty.c, and I'm sure that the solution is to write a similar set of C functions to act as a scheme interface to do what I want. However, I suspect I don't understand the code well enough at this point to do that correctly.

I'd be willing to give it a shot if I thought I had a sufficient quantity of tips on how to get it done (I started to say 'pointers' on how to get it done, but I suspected that would only lead to a long string of programmer jokes that might derail this thread :-D ).

It seems to me that this would be a good thing to have available for any application that might embed Gambit and/or communicate with a process running the Gambit interpreter. I don't think the applicability would be in any way limited to slime/swank (though, admittedly, that is my primary motivation for having it).

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