With this patch, these two lines
(vector-fill! vec fill)
(vector-fill! vec fill 0 end)
run at the same speed; before, the second one was much slower.
This patch also makes it an error to call vector-fill! with a non-vector
array. The previous implementation did not work correctly in this case.
* libguile/vectors.c (SCM_VALIDATE_MUTABLE_VECTOR): Better error message.
(vector-fill!): Handle optional arguments start, end. Do not attempt
to handle non-vector arrays. Rename the C binding to
scm_vector_fill_partial_x.
(scm_vector_fill_x): Reuse scm_vector_fill_partial_x.
* module/srfi/srfi-43.scm (vector-fill!): Remove & re-export the core
version instead.