Library with some useful operations for the Either
data type.
Author: Bjoern Peemoeller
Version: November 2020
lefts
:: [Either a b] > [a]
Extracts from a list of Either
all the Left
elements in order.

rights
:: [Either a b] > [b]
Extracts from a list of Either
all the Right
elements in order.

isLeft
:: Either a b > Bool
Return True
if the given value is a Left value, False
otherwise.

isRight
:: Either a b > Bool
Return True
if the given value is a Right value, False
otherwise.

fromLeft
:: Either a b > a
Extract the value from a Left
constructor.

fromRight
:: Either a b > b
Extract the value from a Right
constructor.

partitionEithers
:: [Either a b] > ([a],[b])
Partitions a list of Either
into two lists.

Extracts from a list of 
Extracts from a list of 
Return

Return

Extract the value from a 
Extract the value from a 
Partitions a list of 