Combine chopped cranberries, sugar, pineapple (including juice), lime juice, and walnuts in a bowl and stir. Cover and chill for at least one hour. (or up to overnight)Add heavy cream to a large bowl. Whip with an electric mixer (you can do it by hand but it will take much longer) until stiff peaks form. Stir in marshmallows. Stir in cranberry mixture. Cover and chill for 4 hours or up to overnight. Serve cold.