@hackage geojson-types0.1.3
GeoJSON data types including JSON/BSON conversion.
Installation
Tested Compilers
Dependencies (6)
Dependents (1)
@hackage/acme-everything
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