Bryan O'Sullivan wrote:
Andrew Coppin wrote:
On the other hand, this is the anti-theisis of Haskell. We start with a
high-level, declarative program, which performs horribly, and end up
with a manually hand-optimised blob that's much harder to read but goes
way faster.
Buh? This is hard to read?
Look closer: it's hardER to read.
mean xs = sum xs / fromIntegral (length xs)
mean = go 0 0 n
where
go s l x
| x > m = s / fromIntegra l
| otherwise = go (s+x) (l+1) (x+1
One version makes it instantly clear, at a glance, what is happening.
The other requires you to mentally walk round a look, imperative style,
to figure out what's happening. It's not a *big* deal, but it's unfortunate.
I'm more worried about what happens in less trivial examples. [Let's
face it, who wants to compute the sum of the numbers from 1 to N?]
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