Safe.Failure

safe-failure-0.2: Partial functions from the prelude with a MonadFailure interface

Safe.Failure

Portability	portable
Stability	in-progress
Maintainer	pepeiborra@gmail.com

Contents

List Functions
Maybe functions
Other Prelude functions
Useful combinators
Assertions
IO functions
Exceptions

Description

A library for safe functions, based on standard functions that may crash.

This module reexports versions which produce exceptions in an arbitrary MonadFailure monad.

Synopsis

head :: MonadFailure HeadFailure m => [a] -> m a

tail :: MonadFailure TailFailure m => [a] -> m [a]

init :: MonadFailure InitFailure m => [a] -> m [a]

last :: MonadFailure LastFailure m => [a] -> m a

minimum :: (Ord a, MonadFailure MinimumFailure m) => [a] -> m a

maximum :: (Ord a, MonadFailure MaximumFailure m) => [a] -> m a

foldr1 :: MonadFailure Foldr1Failure m => (a -> a -> a) -> [a] -> m a

foldl1 :: MonadFailure Foldl1Failure m => (a -> a -> a) -> [a] -> m a

at :: MonadFailure IndexFailure m => [a] -> Int -> m a

lookup :: (Eq a, MonadFailure (LookupFailure a) m) => a -> [(a, b)] -> m b

fromJust :: MonadFailure FromJustFailure m => Maybe a -> m a

read :: (Read a, MonadFailure ReadFailure m) => String -> m a

def :: a -> Maybe a -> a

note :: Exception e => String -> Either e a -> a

assert :: (MonadFailure e m, Exception e) => Bool -> v -> e -> m v

readFile :: (MonadFailure IOException m, MonadIO m) => FilePath -> m String

data SafeException = forall e . Exception e => SafeException e

data HeadFailure = HeadFailure

data TailFailure = TailFailure

data InitFailure = InitFailure

data LastFailure = LastFailure

data MaximumFailure = MaximumFailure

data MinimumFailure = MinimumFailure

data Foldl1Failure = Foldl1Failure

data Foldr1Failure = Foldr1Failure

data IndexFailure = IndexFailure Int

data LookupFailure a = LookupFailure a

data FromJustFailure = FromJustFailure

data ReadFailure = ReadFailure String

List Functions

head :: MonadFailure HeadFailure m => [a] -> m a

Source

tail :: MonadFailure TailFailure m => [a] -> m [a]

Source

init :: MonadFailure InitFailure m => [a] -> m [a]

Source

last :: MonadFailure LastFailure m => [a] -> m a

Source

minimum :: (Ord a, MonadFailure MinimumFailure m) => [a] -> m a

Source

maximum :: (Ord a, MonadFailure MaximumFailure m) => [a] -> m a

Source

foldr1 :: MonadFailure Foldr1Failure m => (a -> a -> a) -> [a] -> m a

Source

foldl1 :: MonadFailure Foldl1Failure m => (a -> a -> a) -> [a] -> m a

Source

at :: MonadFailure IndexFailure m => [a] -> Int -> m a

Source

lookup :: (Eq a, MonadFailure (LookupFailure a) m) => a -> [(a, b)] -> m b

Source

 lookupJust key = fromJust . lookup key

Maybe functions

fromJust :: MonadFailure FromJustFailure m => Maybe a -> m a

Source

Other Prelude functions

read :: (Read a, MonadFailure ReadFailure m) => String -> m a

Source

Useful combinators

def :: a -> Maybe a -> a

Source

def, use it to return a default value in the event of an error.

E.g. you can define a version of tail which returns a default value when the list is empty

  tailDef defaultValue = def defaultValue . tail

note :: Exception e => String -> Either e a -> a

Source

note, use it to fail with an annotated runtime error

Assertions

assert :: (MonadFailure e m, Exception e) => Bool -> v -> e -> m v

Source

Assert a value to be true. If true, returns the first value as a succss. Otherwise, returns the second value as a failure.

IO functions

readFile :: (MonadFailure IOException m, MonadIO m) => FilePath -> m String

Source

The standard readFile function with any IOExceptions returned as a failure instead of a runtime exception.

Exceptions

data SafeException

Source

Constructors

forall e . Exception e => SafeException e

Instances

data HeadFailure

Source

Constructors

HeadFailure

Instances

Show HeadFailure

Typeable HeadFailure

Exception HeadFailure

Throws HeadFailure (Caught SafeException l)

data TailFailure

Source

Constructors

TailFailure

Instances

Show TailFailure

Typeable TailFailure

Exception TailFailure

Throws TailFailure (Caught SafeException l)

data InitFailure

Source

Constructors

InitFailure

Instances

Show InitFailure

Typeable InitFailure

Exception InitFailure

Throws InitFailure (Caught SafeException l)

data LastFailure

Source

Constructors

LastFailure

Instances

Show LastFailure

Typeable LastFailure

Exception LastFailure

Throws LastFailure (Caught SafeException l)

data MaximumFailure

Source

Constructors

MaximumFailure

Instances

Show MaximumFailure

Typeable MaximumFailure

Exception MaximumFailure

Throws MaximumFailure (Caught SafeException l)

data MinimumFailure

Source

Constructors

MinimumFailure

Instances

Show MinimumFailure

Typeable MinimumFailure

Exception MinimumFailure

Throws MinimumFailure (Caught SafeException l)

data Foldl1Failure

Source

Constructors

Foldl1Failure

Instances

Show Foldl1Failure

Typeable Foldl1Failure

Exception Foldl1Failure

Throws Foldl1Failure (Caught SafeException l)

data Foldr1Failure

Source

Constructors

Foldr1Failure

Instances

Show Foldr1Failure

Typeable Foldr1Failure

Exception Foldr1Failure

Throws Foldr1Failure (Caught SafeException l)

data IndexFailure

Source

Constructors

IndexFailure Int

Instances

Show IndexFailure

Typeable IndexFailure

Exception IndexFailure

Throws IndexFailure (Caught SafeException l)

data LookupFailure a

Source

Constructors

LookupFailure a

Instances

Typeable1 LookupFailure

Show a => Show (LookupFailure a)

(Typeable a, Show a) => Exception (LookupFailure a)

(Typeable a, Show a) => Throws (LookupFailure a) (Caught SafeException l)

data FromJustFailure

Source

Constructors

FromJustFailure

Instances

Show FromJustFailure

Typeable FromJustFailure

Exception FromJustFailure

Throws FromJustFailure (Caught SafeException l)

data ReadFailure

Source

Constructors

ReadFailure String

Instances

Show ReadFailure

Typeable ReadFailure

Exception ReadFailure

Throws ReadFailure (Caught SafeException l)

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