geojson-types: GeoJSON data types including JSON/BSON conversion.

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

Modules

[Index]

Downloads

• geojson-types-0.1.3.tar.gz [browse] (Cabal source package)
• Package description (as included in the package)

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Package maintainers

• alios

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