Re: Too much of a good thing? Per Bothner 11 Apr 2003 05:55 UTC

Sergei Egorov wrote:
> <Flame>
> I think that most of the operations that generate vectors element-by-element
> are useless, especially when the performance is the same as in making a list
> first and then turning it into a vector.

- which of course is never.

> The reason for the existence of vectors
> is constant-time access by index and smaller memory footprint; everything
> else is better done with lists.

I'd say: (almost) everything is better done with vectors, if you
care about performance at all.

> Having one humongous SRFI for lists pretty
> much solves the problem; there is no need to replicate it for every "linear"
> data structure. What Scheme needs is more orthogonality, not less, and
> this SRFI (together with large part of Olin's string-lib) just adds more
> names,
> not more functionality. Orthogonal approach is to abstract over the
> concept of "sequence" (this is not the same as giving "generic" versions
> of all the functions with switch by pair? / string? / vector?) and have
> a good SRFI for high-order functions like COMPOSE, NEGATE,
> CURRY, BIND, etc. Only in places where sequences are different
> from each other do we need new functions; in case of vectors, they
> support effective direct access to / modification of content.

This I very much agree with - however it is very different from
the historical "Scheme way of doing things."  (Kawa does have vectors,
lists, strings, and uniform-vectors all special cases of sequences.)

> I suggest to drop everything that is not related to the main purpose
> of vector's existance: constant-time indexed access.

Linear-time operations, such as iterating over all the elements of a
sequence, are also typically much faster using vectors, thanks
to better cache utilization.
--
	--Per Bothner
xxxxxx@bothner.com   http://per.bothner.com/