There is an extract-5 in radix-delete for some reason.
I corrected this shortly after I posted that version, I guess I replaced those manually? very odd.
Reusing the name list->radix for the helper in (radix . elements) seems a bit inelegant to me.
I actually should've moved that into list->radix awhile ago, apply also has a bit of overhead that this avoids.
However, my suggestion is to construct the modulo piece first, then write a simple loop from below the modulo downward to zero and append the partial result to the new piece. Since the radix is accessed with radix-ref-height the same amount of accessing work is done by iterating backward. However, this way you would be appending to a piece of constant length at each step, which is linear behavior overall, whereas in your current version each step appends to a piece of linearly increasing length, which is quadratic behavior overall. Additionally, there is nothing forcing you to stick with vector->list and append!. You can have a helper deal with each new piece by consing a series of vector-refs backwards onto the result list, eliminating the need for vector->list and ditching append! and its import entirely.
This is a awesome suggestion!
(define (radix->list radix-struct)
(define length (radix-length radix-struct))
(define (vector->partial-list vector list)
(let vector->partial-list-iter ((list list) (index 31))
(if (= index 0)
(cons (vector-ref vector index) list)
(vector->partial-list-iter
(cons (vector-ref vector index) list)
(- index 1)))))
(let radix->list-iter
((list
(vector->list
(vector-copy
(radix-ref-height radix-struct length 1)
0
(modulo length 32))))
(position
(- length 32 (modulo length 32))))
(if (< position 0)
list
(radix->list-iter
(vector->partial-list
(radix-ref-height radix-struct position 1)
list)
(- position 32)))))From your ease of use of named lets and the continuation trick of naive-append-vector!, I doubt that.
Thanks anon.