A library that performs fast, accurate conversion between double
precision floating point and text. This library is implemented as
bindings to the C++ double-conversion library written by Florian Loitsch
at Google: http://code.google.com/p/double-conversion/.
The Text versions of these functions are about 30 times faster than the
default show implementation for the Double type. The ByteString versions
are slower than the Text versions; roughly half the speed. (This seems
to be due to the cost of allocating ByteString values via malloc.)
As a final note, be aware that the bytestring-show package is about 50%
slower than simply using show.
Obtained from: FreeBSD Haskell