| Portability | portable |
|---|---|
| Maintainer | jmillikin@gmail.com |
Data.FailableList
Description
A list-like type for lazy streams, which might terminate with an error.
This module uses common names and so is designed to be imported qualified:
import qualified Data.FailableList as FL
- data FailableList e a
- = Next a (FailableList e a)
- | Done
- | Fail e
- null :: FailableList e a -> Bool
- append :: FailableList e a -> FailableList e a -> FailableList e a
- map :: (a -> b) -> FailableList e a -> FailableList e b
- mapEither :: (a -> Either e b) -> FailableList e a -> FailableList e b
- concatMap :: (a -> FailableList e b) -> FailableList e a -> FailableList e b
- foldr :: (a -> b -> b) -> b -> (e -> b) -> FailableList e a -> b
- foldl :: (b -> a -> b) -> b -> FailableList e a -> Either e b
- unfoldr :: (b -> Either e (Maybe (a, b))) -> b -> FailableList e a
- length :: FailableList e a -> Int
Documentation
data FailableList e a Source
A list-like type for lazy sequences which might terminate with an error.
Standard lists can be converted to failable lists using
Prelude.foldr Next Done.
Constructors
| Next a (FailableList e a) | |
| Done | |
| Fail e |
Instances
| Monad (FailableList e) | |
| Functor (FailableList e) | |
| MonadFix (FailableList e) | |
| MonadPlus (FailableList e) | |
| Applicative (FailableList e) | |
| Foldable (FailableList e) | |
| Traversable (FailableList e) | |
| Alternative (FailableList e) | |
| (Eq e, Eq a) => Eq (FailableList e a) | |
| (Show e, Show a) => Show (FailableList e a) | |
| Monoid (FailableList e a) |
null :: FailableList e a -> BoolSource
Like the standard null function.
append :: FailableList e a -> FailableList e a -> FailableList e aSource
Like the standard ++ function.
map :: (a -> b) -> FailableList e a -> FailableList e bSource
Like the standard map function.
mapEither :: (a -> Either e b) -> FailableList e a -> FailableList e bSource
Like the standard map function, but the mapping function may
return an error.
concatMap :: (a -> FailableList e b) -> FailableList e a -> FailableList e bSource
Like the standard concatMap function.
foldr :: (a -> b -> b) -> b -> (e -> b) -> FailableList e a -> bSource
foldl :: (b -> a -> b) -> b -> FailableList e a -> Either e bSource
unfoldr :: (b -> Either e (Maybe (a, b))) -> b -> FailableList e aSource
Like the standard Data.List.unfoldr function, but the step function
may return an error.