Combine raspberries, sugar, cornstarch, tapioca and lemon juice. Set aside.
Combine flours and salt in medium bowl. Cut butter into small pieces and toss with flour mixture. Cut in butter until mixture looks like coarse crumbs. Sprinkle with water, one tablespoon at a time, stirring until all the mixture is moistened. Divide dough in half and form into two discs. Wrap each disc in plastic and refrigerate 30 minutes.
Preheat the oven to 375ºF (190ºC). Roll out one disc to fit pie pan and place in pan. Trim edges even with the rim of the pan. Roll out second disc. Cut into ½ in.strips. Stir filling and pour into pie pan. Weave strips of dough into lattice pattern on top of filling, pressing ends into rim of crust. Brush edge with water and fold bottom edge over strips, sealing and fluting edge. Brush top of pie with water and sprinkle with sugar. Bake 50-60 minutes, until top is golden brown, shielding edges with foil if needed to prevent overbrowning.