|The Either type, and associated operations.
The Either type represents values with two possibilities: a value of
type Either a b is either Left a or Right b.
The Either type is sometimes used to represent a value which is
either correct or an error; by convention, the Left constructor is
used to hold an error value and the Right constructor is used to
hold a correct value (mnemonic: "right" also means "correct").
|Case analysis for the Either type.
If the value is Left a, apply the first function to a;
if it is Right b, apply the second function to b.
|Produced by Haddock version 0.8|