It's rather that some considered the IArray API to be
inadequate most of the time. Really, H98 arrays aren't very
good at anything they do. For collective operations, you are
supposed to convert the array to a list, work on the list and
then convert it back to an array which just seems wrong.
I am unconvinded that this is any more wrong than using a for
loop in an imperative language. Remember that the lists are
lazy, so it’s misleading to say “convert the array to a list”
since what happens most of the time is that elements are taken
out of the array and passed to the processing function and then
thrown away before the next element is processed.
You're still needlessly allocating and then garbage collecting memory
though.
My personal feeling is that Haskell programmers use lists a lot when
what they really want are "streams" (in the sense of the stream-fusion
library). I don't want you to actually *make* a physical list, I just
want to abstract over something that sequentially generates data.
But then, lists are in the standard Prelude, and hard-wired into the
language syntax. Streams aren't exposed by any moderately standard
library. Even the stream-fusion library treats streams as a sort of
"under the covers" thing to deforest lists. My humble opinion is that
half the time when people create physical lists, what they really mean
is a data pipeline that doesn't need to physically materialise at all.
But anyway... Haskell '98 arrays may have fancy indexing, but I've
always wished that there had been a plain ordinary integer-indexed array
construct, with the fancy indexing implemented on top of that, so your
use of fancy indexing is /optional/. I get the distinct impression that
the default array libraries are so barren just because nobody really
used them much, and that was then and this is now, and it's a major pain
to break something that so much code is written against...
I just hope we don't end up with a bazillion different array
implementations popping up. But we'll see.
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