Proposal: Export Data.Word.Word from Prelude

[Malcolm Wallace]

On 10 Aug 2014, at 07:04, Ivan Lazar Miljenovic wrote:

> I'm +1 on the re-exporting (I would be tempted to go the whole hog and
> re-export all the Word* types as well).


I was involved in the discussions when the Word type was originally added to Haskell, primarily for the use of the FFI.  As I recall, people were deeply uncomfortable that there should even be a Word type, with unspecified precision.  The types Word8, Word16, Word32, and Word64 were entirely uncontroversial, because you know what you are dealing with.  The primary use of the Word* types was to represent machine words (bytes, half-words, etc), enabling (for instance) bit-twiddling of individual components of the word.  With an unknown-precision Word value, you can guarantee nothing about whether your bit-operation will work.  I believe the use of unknown-precision Word to represent non-negative integers was the winning justification, but it remains controversial in the same way that Int (rather than Int32, or Integer) does.  Lack of clarity over whether or when a number overflows is a pretty bad downside.  Pragmatically, it may work OK for most people most of the time.  But the Haskell way is to prefer correctness.

Regards,
    Malcolm