| Copyright | Plow Technologies LLC |
|---|---|
| License | MIT License |
| Maintainer | Scott Murphy |
| Safe Haskell | None |
| Language | Haskell2010 |
Database.Groundhog.Converters
Description
This is a library for creating composable converters between datatypes for the purpose of inserting into a groundhog database.
The idea is to get from a representation a, which does not have a type class 'PersistEntity a'
to one b, which has that type class defined.
This allows lightweight types libraries to coexist with nice database representations.
- makeConverter :: (a -> b) -> (b -> a) -> Converter a b
- flipConverter :: Converter a b -> Converter b a
- composeConverter :: Converter a b -> Converter b c -> Converter a c
- fmapConverter :: Functor f => Converter a b -> Converter (f a) (f b)
- bicomposeConverter :: Converter a b -> Converter c d -> Converter (a, c) (b, d)
- firstConverter :: Converter a b -> Converter (a, c) (b, c)
- secondConverter :: Converter a b -> Converter (c, a) (c, b)
- jsonConverter :: (ToJSON a, FromJSON a) => Converter a ByteString
- integerConverter :: Converter Integer Int64
- mapConverter :: Ord k => Converter (Map k v) [(k, v)]
- bimapConverter :: (Ord a, Ord b) => Converter (Bimap a b) [(a, b)]
- intMapConverter :: Converter (IntMap a) [(Int, a)]
- type Converter a b = (a -> b, b -> a)
Documentation
Arguments
| :: (a -> b) | Convert developer-facing type to database-storable type |
| -> (b -> a) | Convert database-storable type to developer-facing type |
| -> Converter a b |
Make a converter
There are preconditions on the input functions:
makeConverter f g
f (g x) = x
g (f x) = x
flipConverter :: Converter a b -> Converter b a Source
Reverse the direction of a converter
composeConverter :: Converter a b -> Converter b c -> Converter a c Source
Compose two converters
fmapConverter :: Functor f => Converter a b -> Converter (f a) (f b) Source
Map a converter over a functor
bicomposeConverter :: Converter a b -> Converter c d -> Converter (a, c) (b, d) Source
compose a First and Second Converter
firstConverter :: Converter a b -> Converter (a, c) (b, c) Source
Convert only the first element of a pair
secondConverter :: Converter a b -> Converter (c, a) (c, b) Source
Convert only the second element of a pair
jsonConverter :: (ToJSON a, FromJSON a) => Converter a ByteString Source
Convert via to and from JSON
mapConverter :: Ord k => Converter (Map k v) [(k, v)] Source
Convert a Map to a list of key-value pairs
bimapConverter :: (Ord a, Ord b) => Converter (Bimap a b) [(a, b)] Source
Convert a Bimap to a list of key-value pairs
intMapConverter :: Converter (IntMap a) [(Int, a)] Source