While discussing an improved IO interface for uvector, Bryan O’Sullivan made the following request:
<pumpkin_> bos: well, dons said it would be nice to have
an O(1) conversion from UArrs to strict
ByteStrings and back again
<dons> i'm not sure its possible though :)
<bos> pumpkin_: yes, it would be nice. i would also like a pony.
And of course, this being Haskell, you can have a pony! Though it might be more abstract than what you were expecting.
Control.Monad.Writer 
As discussed on IRC, this isn’t a pony, it’s a horse with a horn attached to its forehead.
Haha. :-)
That’s nice :)
Dude, that’s not a pony, that’s a unicorn. Type error!