[Haskell-cafe] help with safecopy + acid-state

Felipe Almeida Lessa felipe.lessa at gmail.com
Mon Jan 30 20:16:55 CET 2012

On Mon, Jan 30, 2012 at 4:46 PM, Johannes Waldmann
<waldmann at imn.htwk-leipzig.de> wrote:
> Thanks - which zero? (there are two of them.)

You should not change the deriveSafeCopy of your old data type.  The
only allowed change is renaming your data type (see below).  You
should increment the version of the new version of your data type,
akin to releasing a new version of a library.

> Can I really rename  old.T => new.T_orig ?
> It looks as if then tries to load the wrong acid-state snapshot.

The name of your data type doesn't matter as acid-state doesn't store
that on the disk.



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