Database.Postgis.Trivial.Storable

Allows PostGIS to work with geospatial data enclosed in Traversable data structures with Storable Vectors as the most inner structures.

Example of suitable data types for LineString and Polygon.

{-# LANGUAGE TypeFamilies #-}

import qualified Data.Vector.Storable as VS
import Foreign.Storable.Record as Store
import Foreign.Storable ( Storable (..) )

data GeoDuo = GeoDuo
        { dx :: !Double
        , dy :: !Double
        } deriving (Show, Eq)

storeGeoDuo :: Store.Dictionary GeoDuo
storeGeoDuo = Store.run $
    liftA2 GeoDuo
        (Store.element dx)
        (Store.element dy)

instance Storable GeoDuo where
   sizeOf = Store.sizeOf storeGeoDuo
   alignment = Store.alignment storeGeoDuo
   peek = Store.peek storeGeoDuo
   poke = Store.poke storeGeoDuo

type instance Cast GeoDuo = P2D

instance Castable GeoDuo where
    toPointND (GeoDuo y x) = Point2D x y
    fromPointND (Point2D x y) = GeoDuo y x

type LineStringData = VS.Vector GeoDuo
type PolygonData = [VS.Vector GeoDuo]

Documentation

module Database.Postgis.Trivial.Types

module Database.Postgis.Trivial.Cast

module Database.Postgis.Trivial.Storable.PointND

module Database.Postgis.Trivial.Storable.Geometry