Provides data types, lens operators and (de)serialization
of GeoJSON data to/from JSON and BSON using aeson and bson.
This library uses a the lens library a lot. It provides
Iso / Prism to convert from and to GeoJSON objects.
e.g. to convert a latitude/longitude given as a pair of
Double to a Position, use the _Position Iso as a
Getter on that pair:
_Position :: BaseType t => Iso' (t, t) (Position t)
pos :: Position Double
pos = (57.324, 7.2342) ^. _Position
to then convert it to a Point object use _Point:
_Point :: Iso' (Position t) (GeoJSON Point t)
p :: GeoJSON Point Double
p = pos ^. _Point
ps :: GeoJSON MultiPoint Double
ps = [p,p,p,p] ^. _MultiPoint
The library also provides type classes for working polymorphic
over user defined data types.
e.g. for a data type:
data Location =
Location {
locationName :: String,
locationLat :: Double,
locationLon :: Double
}
one can implement the type class HasGeoJSON to provide a
Getter to a any GeoJSON object. In this example a Point.
instance HasGeoJSON Point Double Location where
geoJSON = to $ \loc ->
(locationLat loc, locationLon loc) ^. _Position . _Point
