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Re: Too much of a good thing?



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
per@xxxxxxxxxxx   http://per.bothner.com/