>>13
I just noticed something strange about copy-slice-append-iter. Correct me if I'm wrong but it seems to me that, for every leaf vector except the first, each leaf vector is looked up twice, starting all the way from the root, once by the second vector-copy! in the current round, and again by the first vector-copy! in the next round. These two calls:
(radix-ref-depth read-radix (+ read-position 32) 5)
(radix-ref-depth read-radix read-position 5)
perform the exact same work across a pair of consecutive rounds, where read-position has been incremented by either 32 or the distance to read-end. I would think that avoiding such duplicate work at the algorithm level would rate higher than whether SIMD was available.