libghc-convertible-dev binary package in Ubuntu Precise i386

 convertible provides a typeclass with a single function
 that is designed to help convert between different types: numeric
 values, dates and times, and the like. The conversions perform bounds
 checking and return a pure Either value. This means that you need
 not remember which specific function performs the conversion you
 desire.
 .
 Also included in the package are optional instances that provide
 conversion for various numeric and time types, as well as utilities
 for writing your own instances.
 .
 Finally, there is a function that will raise an exception on
 bounds-checking violation, or return a bare value otherwise,
 implemented in terms of the safer function described above.
 .
 Convertible is also used by HDBC 2.0 for handling marshalling of
 data to/from databases.
 .
 Convertible is backed by an extensive test suite and passes tests
 on GHC and Hugs.

Source package