[Haskell-cafe] Creating a instance for (Storable Text)

Any ideas on how I'd write this instance? I know for it to be storable it needs a size, couldn't I just get the length of the text? Has anyone did anything similar? I ran into a surprise when trying to use storable-record and derive-storable and tried using them with a record that contained a Text field. My end goal is having a vector of records that could contain Text, UTCTime, or other similarly complex types which I can write as an mmap to disk and then read back to the original format. Thanks!