Cook 2 cups dates, 1/2 cup sugar, and 1/2 cup water until thick. Cool. Sift together 4 cups flour, 1 teaspoon baking soda, and 1 teaspoon salt. Cream 1 cup butter and add 1 cup sugar and 1 cup brown sugar; cream well. Blend in 3 eggs and 1 teaspoon vanilla. Beat well. Add dry ingredients; mix. Stir in 1 cup chopped nuts and the cooked date mixture. Drop dough by the teaspoonfuls onto greased sheets. Bake until golden brown.