Safe Haskell  Safe 

Language  Haskell2010 
Synopsis
 data Migration = Migration {
 runMigration :: forall a b. (Data a, Data b) => a > b > Maybe a
 runSafeMigration :: (Data a, Data b) => Migration > a > b > a
 castMigration :: Migration
 newtypeMigration :: Migration
 userMigration :: (Typeable c, Typeable d) => (c > d) > Migration
 migrationTo2 :: Typeable t => (forall a b c. (Typeable a, Typeable b, Typeable c) => t b c > a > Maybe (t b c)) > Migration
 constMigrationFrom2 :: Typeable t => (forall a b c. (Typeable a, Typeable b, Typeable c) => t b c > Maybe a) > Migration
 migrationTo1 :: Typeable t => (forall a b. (Typeable a, Typeable b) => t b > a > Maybe (t b)) > Migration
Documentation
Migration  

runSafeMigration :: (Data a, Data b) => Migration > a > b > a Source #
Run a migration and insert the new initial state in case of failure.
castMigration :: Migration Source #
Try to migrate by casting the first type into the second
newtypeMigration :: Migration Source #
Migrate a value into a newtype wrapping
userMigration :: (Typeable c, Typeable d) => (c > d) > Migration Source #
If you have a specific type that you would like to be migrated to a specific other type,
you can create a migration for this.
For example: userMigration (toInteger :: Int > Integer)
migrationTo2 :: Typeable t => (forall a b c. (Typeable a, Typeable b, Typeable c) => t b c > a > Maybe (t b c)) > Migration Source #