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

Michael Snoyman michael at snoyman.com
Thu Nov 24 18:23:53 UTC 2016


It can't be done. Instances of Storable need to have a fixed serialized
size, and Text values don't.

On Thu, Nov 24, 2016, 8:21 PM Cody Goodman <codygman.consulting at gmail.com>
wrote:

> 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!
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