Library with some useful operations for the Either
            data type.
          
Author: Bjoern Peemoeller
Version: March 2015
| lefts
                  ::  [Either a b] -> [a]Extracts from a list of Eitherall theLeftelements in order. | 
| rights
                  ::  [Either a b] -> [b]Extracts from a list of Eitherall theRightelements in order. | 
| isLeft
                  ::  Either a b -> BoolReturn Trueif the given value is aLeft-value,Falseotherwise. | 
| isRight
                  ::  Either a b -> BoolReturn Trueif the given value is aRight-value,Falseotherwise. | 
| fromLeft
                  ::  Either a b -> aExtract the value from a Leftconstructor. | 
| fromRight
                  ::  Either a b -> bExtract the value from a Rightconstructor. | 
| partitionEithers
                  ::  [Either a b] -> ([a],[b])Partitions a list of Eitherinto two lists. | 
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                      Extracts from a list of  | 
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                      Extracts from a list of  | 
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                      Return  
 | 
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                      Return  
 | 
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                      Extract the value from a  
 | 
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                      Extract the value from a  
 | 
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                      Partitions a list of  |