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| Data.Either | | Portability | portable | | Stability | experimental | | Maintainer | libraries@haskell.org |
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| Description |
| The Either type, and associated operations.
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| Synopsis |
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| Documentation |
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| data Either a b |
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").
| | Constructors | |  Instances | |
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| either :: (a -> c) -> (b -> c) -> Either a b -> c |
| 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.
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| lefts :: [Either a b] -> [a] |
| Extracts from a list of Either all the Left elements
All the Left elements are extracted in order.
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| rights :: [Either a b] -> [b] |
| Extracts from a list of Either all the Right elements
All the Right elements are extracted in order.
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| partitionEithers :: [Either a b] -> ([a], [b]) |
| Partitions a list of Either into two lists
All the Left elements are extracted, in order, to the first
component of the output. Similarly the Right elements are extracted
to the second component of the output.
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| Produced by Haddock version 2.4.2 |
