A basic pie chart.

Note that template haskell is used to derive accessor functions (see Data.Accessor) for each field of the following data types:

• PieLayout
• PieChart
• PieItem

These accessors are not shown in this API documentation. They have the same name as the field, but with the trailing underscore dropped. Hence for data field f_::F in type D, they have type

   f :: Data.Accessor.Accessor D F