[Haskell-cafe] attoparsec double precision, quickCheck and aeson

[Bryan O'Sullivan]

  On Wed, Jun 6, 2012 at 6:20 AM, Doug McIlroy <doug at cs.dartmouth.edu>wrote:

> Last I looked (admittedly quite a while ago), the state of
> the art was strtod in http://www.netlib.org/fp/dtoa.c.
> (Alas, dtoa.c achieves calculational perfection via a
> murmuration of #ifdefs.)
>

That was indeed the state of the art for about three decades, until Florian
Loitsch showed up in 2010 with an algorithm that is usually far faster:
http://www.serpentine.com/blog/2011/06/29/here-be-dragons-advances-in-problems-you-didnt-even-know-you-had/

Unfortunately, although I've written Haskell bindings to his library, said
library is written in C++, and our FFI support for C++ libraries is
negligible and buggy. As a result, that code is disabled by default.

It's disheartening to hear that important Haskell code has
> needlessly fallen from perfection--perhaps even deliberately.


Indeed (and yes, it's deliberate). If I had the time to spare, I'd attempt
to fix the situation by porting Loitsch's algorithm to Haskell or C, but
either one would be a lot of work - the library is 5,600 lines of tricky
code.
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