Portability | portable |
---|---|

Stability | experimental |

Additional monadic random functions, based on `MonadRandom`

.

- shuffle :: MonadRandom m => [a] -> m [a]
- shuffleSeq :: MonadRandom m => Seq a -> m [a]
- sample :: MonadRandom m => Int -> [a] -> m [a]
- sampleSeq :: MonadRandom m => Int -> Seq a -> m [a]
- choiceExtract :: MonadRandom m => [a] -> m (Maybe ([a], a))
- choiceExtractSeq :: MonadRandom m => Seq a -> m (Maybe (Seq a, a))
- choice :: MonadRandom m => [a] -> m a
- safeChoice :: MonadRandom m => [a] -> Maybe (m a)
- iterativeChoice :: MonadRandom m => [a] -> m a
- choiceSeq :: MonadRandom m => Seq a -> m a
- safeChoiceSeq :: MonadRandom m => Seq a -> Maybe (m a)
- choiceArray :: (MonadRandom m, IArray arr a, Ix i, Random i) => arr i a -> m a
- choices :: MonadRandom m => [a] -> m [a]
- safeChoices :: MonadRandom m => [a] -> Maybe (m [a])
- choicesArray :: (MonadRandom m, IArray arr a, Ix i, Random i) => arr i a -> m [a]

# Random functions

## Shuffling

shuffle :: MonadRandom m => [a] -> m [a]Source

Shuffle a list randomly. The method is based on Oleg Kiselyov's
*perfect shuffle* http://okmij.org/ftp/Haskell/perfect-shuffle.txt,
but much simpler because it uses existing data structures. The efficiency
of both methods should be comparable.

*Complexity:* O(n * log n), where *n* is the length of the input list.

shuffleSeq :: MonadRandom m => Seq a -> m [a]Source

Shuffle a sequence randomly. This is being used by `shuffle`

,
so it logically uses the same method.

*Complexity:* O(n * log n), where *n* is the length of the input sequence.

## Sampling

sample :: MonadRandom m => Int -> [a] -> m [a]Source

Take a random sample from a list.

*Complexity:* O(n + m * log n), where *n* is the length of the input list
and *m* is the sample size.

sampleSeq :: MonadRandom m => Int -> Seq a -> m [a]Source

Take a random sample from a sequence.

*Complexity:* O(m * log n), where *n* is the length of the input sequence
and *m* is the sample size.

## Choice

choiceExtract :: MonadRandom m => [a] -> m (Maybe ([a], a))Source

Randomly choose and extract an element from a list.

*Complexity:* O(n), where *n* is the length of the input list.

choiceExtractSeq :: MonadRandom m => Seq a -> m (Maybe (Seq a, a))Source

Randomly choose and extract an element from a sequence.

*Complexity:* O(log n), where *n* is the length of the input sequence.

choice :: MonadRandom m => [a] -> m aSource

Select a random element from a list.

*Partial function:* This function is only defined on non-empty lists.

*Complexity:* O(n), where *n* is the length of the input list.

safeChoice :: MonadRandom m => [a] -> Maybe (m a)Source

Safely select a random element from a list.

*Complexity:* O(n), where *n* is the length of the input list.

iterativeChoice :: MonadRandom m => [a] -> m aSource

Select a random element from a list, traversing the list only once.

*Partial function:* This function is only defined on non-empty lists
with a length below (`maxBound`

+ 1 :: Int).

*Complexity:* O(n), where *n* is the length of the input list.

choiceSeq :: MonadRandom m => Seq a -> m aSource

Select a random element from a sequence.

*Partial function:* This function is only defined on non-empty sequences.

*Complexity:* O(log n), where *n* is the length of the input sequence.

safeChoiceSeq :: MonadRandom m => Seq a -> Maybe (m a)Source

Safely select a random element from a sequence.

*Complexity:* O(log n), where *n* is the length of the input sequence.

choiceArray :: (MonadRandom m, IArray arr a, Ix i, Random i) => arr i a -> m aSource

Select a random element from an array.

*Complexity:* O(1).

## Choices

choices :: MonadRandom m => [a] -> m [a]Source

A stream of random elements from a list.

*Partial function:* This function is only defined on non-empty lists.

*Complexity:* O(n) base and O(1) per element.

safeChoices :: MonadRandom m => [a] -> Maybe (m [a])Source

Safely get a stream of random elements from a list.

*Complexity:* O(n) base and O(1) per element, where *n* is the length of
the input list.

choicesArray :: (MonadRandom m, IArray arr a, Ix i, Random i) => arr i a -> m [a]Source

A stream of random elements from an array.

*Complexity:* O(1) per element.