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

[Felipe Almeida Lessa]

On Fri, Jan 27, 2012 at 3:04 PM, Johannes Waldmann
<waldmann at imn.htwk-leipzig.de> wrote:
> data T_orig = T_orig Foo
> $(deriveSafeCopy 0 'base ''T_orig)
> data T = T Foo Bar
> $(deriveSafeCopy 0 'extension ''T)
> instance Migrate T where type MigrateFrom T = T_Orig ...

As you can read from deriveSafeCopy's documentation [1], you need to
increase the version of your data type (e.g. change that zero to one).

HTH,

[1] http://hackage.haskell.org/packages/archive/safecopy/0.6.1/doc/html/Data-SafeCopy.html#v:deriveSafeCopy

-- 
Felipe.