[Haskell-cafe] An interesting paper from Google

Brandon S Allbery KF8NH allbery at ece.cmu.edu
Fri Oct 15 21:24:40 EDT 2010

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On 10/15/10 16:28 , Andrew Coppin wrote:
> I'm surprised about the profiler. They seem really, really impressed with
> it. Which is interesting to me, since I can never seen to get anything
> sensible out of it. It always seems to claim that my program is spending 80%
> of its runtime executing zipWith or something equally absurd. I'm

That just means you haven't internalized managing laziness yet, so you're
seeing thunks get processed by zipWith instead of where they ought to be.
(Not that I'll claim to be any better; I just know why it happens.)

> surprised that there's no tool anywhere which will trivially print out the
> reduction sequence for executing an expression. You'd think this would be
> laughably easy, and yet nobody has done it yet.

Hat hasn't been maintained for years, sigh.  A number of times I could have
used it... and I'm not confident enough of my ability to grok the code.

> Their comments about String are sadly true.

HP's still struggling with that one (I think some people need to realize
that Text and ByteString have different use cases and correspondingly
different data models, and trying to force both into the list API will only
cause grief, but I digress).  I have hope that this situation will improve
in the future.

(Also, I process enough short strings that I'm uncertain of the wisdom of
just using Text or ByteString for everything; this is admittedly a function
of lack of experience.)

- -- 
brandon s. allbery     [linux,solaris,freebsd,perl]      allbery at kf8nh.com
system administrator  [openafs,heimdal,too many hats]  allbery at ece.cmu.edu
electrical and computer engineering, carnegie mellon university      KF8NH
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