Control.Error.Safe

errors-2.1.3: Simplified error-handling

Safe Haskell | Safe
Language | Haskell98

Control.Error.Safe

Contents

- Maybe-compatible functions
- Either-compatible functions
- ExceptT-compatible functions
- MonadPlus-compatible functions

Description

This module extends the `safe` library's functions with corresponding versions compatible with `Either` and `ExceptT`, and also provides a few `Maybe`-compatible functions missing from `safe`.

I suffix the `Either`-compatible functions with `Err` and prefix the `ExceptT`-compatible functions with `try`.

Note that this library re-exports the `Maybe` compatible functions from `safe` in the Control.Error module, so they are not provided here.

The '`Z`'-suffixed functions generalize the `Maybe` functions to also work with anything that implements `MonadPlus`, including:

- Lists
- Most parsers
- `ExceptT` (if the left value is a `Monoid`)

Synopsis

- assertMay :: Bool -> Maybe ()
- rightMay :: Either e a -> Maybe a
- tailErr :: e -> [a] -> Either e [a]
- initErr :: e -> [a] -> Either e [a]
- headErr :: e -> [a] -> Either e a
- lastErr :: e -> [a] -> Either e a
- minimumErr :: Ord a => e -> [a] -> Either e a
- maximumErr :: Ord a => e -> [a] -> Either e a
- foldr1Err :: e -> (a -> a -> a) -> [a] -> Either e a
- foldl1Err :: e -> (a -> a -> a) -> [a] -> Either e a
- foldl1Err' :: e -> (a -> a -> a) -> [a] -> Either e a
- atErr :: e -> [a] -> Int -> Either e a
- readErr :: Read a => e -> String -> Either e a
- assertErr :: e -> Bool -> Either e ()
- justErr :: e -> Maybe a -> Either e a
- tryTail :: Monad m => e -> [a] -> ExceptT e m [a]
- tryInit :: Monad m => e -> [a] -> ExceptT e m [a]
- tryHead :: Monad m => e -> [a] -> ExceptT e m a
- tryLast :: Monad m => e -> [a] -> ExceptT e m a
- tryMinimum :: (Monad m, Ord a) => e -> [a] -> ExceptT e m a
- tryMaximum :: (Monad m, Ord a) => e -> [a] -> ExceptT e m a
- tryFoldr1 :: Monad m => e -> (a -> a -> a) -> [a] -> ExceptT e m a
- tryFoldl1 :: Monad m => e -> (a -> a -> a) -> [a] -> ExceptT e m a
- tryFoldl1' :: Monad m => e -> (a -> a -> a) -> [a] -> ExceptT e m a
- tryAt :: Monad m => e -> [a] -> Int -> ExceptT e m a
- tryRead :: (Monad m, Read a) => e -> String -> ExceptT e m a
- tryAssert :: Monad m => e -> Bool -> ExceptT e m ()
- tryJust :: Monad m => e -> Maybe a -> ExceptT e m a
- tryRight :: Monad m => Either e a -> ExceptT e m a
- tailZ :: MonadPlus m => [a] -> m [a]
- initZ :: MonadPlus m => [a] -> m [a]
- headZ :: MonadPlus m => [a] -> m a
- lastZ :: MonadPlus m => [a] -> m a
- minimumZ :: MonadPlus m => Ord a => [a] -> m a
- maximumZ :: MonadPlus m => Ord a => [a] -> m a
- foldr1Z :: MonadPlus m => (a -> a -> a) -> [a] -> m a
- foldl1Z :: MonadPlus m => (a -> a -> a) -> [a] -> m a
- foldl1Z' :: MonadPlus m => (a -> a -> a) -> [a] -> m a
- atZ :: MonadPlus m => [a] -> Int -> m a
- readZ :: MonadPlus m => Read a => String -> m a
- assertZ :: MonadPlus m => Bool -> m ()
- justZ :: MonadPlus m => Maybe a -> m a
- rightZ :: MonadPlus m => Either e a -> m a

# Maybe-compatible functions

assertMay :: Bool -> Maybe () #

An assertion that fails in the `Maybe` monad

rightMay :: Either e a -> Maybe a #

A `fromRight` that fails in the `Maybe` monad

# Either-compatible functions

tailErr :: e -> [a] -> Either e [a] #

A `tail` that fails in the `Either` monad

initErr :: e -> [a] -> Either e [a] #

An `init` that fails in the `Either` monad

headErr :: e -> [a] -> Either e a #

A `head` that fails in the `Either` monad

lastErr :: e -> [a] -> Either e a #

A `last` that fails in the `Either` monad

minimumErr :: Ord a => e -> [a] -> Either e a #

A `minimum` that fails in the `Either` monad

maximumErr :: Ord a => e -> [a] -> Either e a #

A `maximum` that fails in the `Either` monad

foldr1Err :: e -> (a -> a -> a) -> [a] -> Either e a #

A `foldr1` that fails in the `Either` monad

foldl1Err :: e -> (a -> a -> a) -> [a] -> Either e a #

A `foldl1` that fails in the `Either` monad

foldl1Err' :: e -> (a -> a -> a) -> [a] -> Either e a #

A `foldl1'` that fails in the `Either` monad

atErr :: e -> [a] -> Int -> Either e a #

A (`!!`) that fails in the `Either` monad

readErr :: Read a => e -> String -> Either e a #

A `read` that fails in the `Either` monad

assertErr :: e -> Bool -> Either e () #

An assertion that fails in the `Either` monad

justErr :: e -> Maybe a -> Either e a #

A `fromJust` that fails in the `Either` monad

# ExceptT-compatible functions

tryTail :: Monad m => e -> [a] -> ExceptT e m [a] #

A `tail` that fails in the `ExceptT` monad

tryInit :: Monad m => e -> [a] -> ExceptT e m [a] #

An `init` that fails in the `ExceptT` monad

tryHead :: Monad m => e -> [a] -> ExceptT e m a #

A `head` that fails in the `ExceptT` monad

tryLast :: Monad m => e -> [a] -> ExceptT e m a #

A `last` that fails in the `ExceptT` monad

tryMinimum :: (Monad m, Ord a) => e -> [a] -> ExceptT e m a #

A `minimum` that fails in the `ExceptT` monad

tryMaximum :: (Monad m, Ord a) => e -> [a] -> ExceptT e m a #

A `maximum` that fails in the `ExceptT` monad

tryFoldr1 :: Monad m => e -> (a -> a -> a) -> [a] -> ExceptT e m a #

A `foldr1` that fails in the `ExceptT` monad

tryFoldl1 :: Monad m => e -> (a -> a -> a) -> [a] -> ExceptT e m a #

A `foldl1` that fails in the `ExceptT` monad

tryFoldl1' :: Monad m => e -> (a -> a -> a) -> [a] -> ExceptT e m a #

A `foldl1'` that fails in the `ExceptT` monad

tryAt :: Monad m => e -> [a] -> Int -> ExceptT e m a #

A (`!!`) that fails in the `ExceptT` monad

tryRead :: (Monad m, Read a) => e -> String -> ExceptT e m a #

A `read` that fails in the `ExceptT` monad

tryAssert :: Monad m => e -> Bool -> ExceptT e m () #

An assertion that fails in the `ExceptT` monad

tryJust :: Monad m => e -> Maybe a -> ExceptT e m a #

A `fromJust` that fails in the `ExceptT` monad

tryRight :: Monad m => Either e a -> ExceptT e m a #

A `fromRight` that fails in the `ExceptT` monad

# MonadPlus-compatible functions

tailZ :: MonadPlus m => [a] -> m [a] #

A `tail` that fails using `mzero`

initZ :: MonadPlus m => [a] -> m [a] #

An `init` that fails using `mzero`

headZ :: MonadPlus m => [a] -> m a #

A `head` that fails using `mzero`

lastZ :: MonadPlus m => [a] -> m a #

A `last` that fails using `mzero`

minimumZ :: MonadPlus m => Ord a => [a] -> m a #

A `minimum` that fails using `mzero`

maximumZ :: MonadPlus m => Ord a => [a] -> m a #

A `maximum` that fails using `mzero`

foldr1Z :: MonadPlus m => (a -> a -> a) -> [a] -> m a #

A `foldr1` that fails using `mzero`

foldl1Z :: MonadPlus m => (a -> a -> a) -> [a] -> m a #

A `foldl1` that fails using `mzero`

foldl1Z' :: MonadPlus m => (a -> a -> a) -> [a] -> m a #

A `foldl1'` that fails using `mzero`

atZ :: MonadPlus m => [a] -> Int -> m a #

A (`!!`) that fails using `mzero`

readZ :: MonadPlus m => Read a => String -> m a #

A `read` that fails using `mzero`

assertZ :: MonadPlus m => Bool -> m () #

An assertion that fails using `mzero`

justZ :: MonadPlus m => Maybe a -> m a #

A `fromJust` that fails using `mzero`

rightZ :: MonadPlus m => Either e a -> m a #

A `fromRight` that fails using `mzero`