Re: [Haskell-cafe] ANNOUNCE: vector-bytestring-0.0.0.0

On Wed, Oct 19, 2011 at 9:29 PM, Ketil Malde wrote:

Michael Snoyman writes:

...

sense to try and pursue something like what you're suggesting, but I think the default Show (Vector Word8) should be the one most useful, most of the time, and I think the general consensus seems to be the current ByteString instance fits that role.

Hm.  I think it is slightly weird to display a numeric value (Word8) as a Char.  Also, I would prefer a representation making the type explicit (but unlike ByteString, vector seems to add a type annotation.)  Would you still support the truncating behavior for 'read' and values above 255?

(ByteString has two interfaces, ByteString and .Char8, but as there can be only one Show instance, I see why it works the way it does.)

Perhaps the correct semantic approach would be to have: newtype Char8 = Char8 Word8 But I think that will break far too many applications to try to get it implemented. In an ideal world, I agree with both points: displaying a numeric value as a Char doesn't make sense, and there are definitely issues with the Read instance. However, I still think current behavior is the least of all available evils. Show/Read work properly as a pair and can encode/decode any ByteString, and there's never any presumption that all input to read is valid. Michael