- spec :: Eq a => a -> (a -> b) -> a -> b
- spec' :: Eq a => a -> (a -> b) -> a -> b
- evaluated :: a -> Bool
- specFoldr :: (Speculative f, Eq b) => (Int -> b) -> (a -> b -> b) -> b -> f a -> b
- specFoldl :: (Speculative f, Eq b) => (Int -> b) -> (b -> a -> b) -> b -> f a -> b
- class Foldable f => Speculative f where
- specFoldr1 :: Eq a => (Int -> a) -> (a -> a -> a) -> f a -> a
- specFoldrN :: Eq b => Int -> (Int -> b) -> (a -> b -> b) -> b -> f a -> b
- specFoldl1 :: Eq a => (Int -> a) -> (a -> a -> a) -> f a -> a
- specFoldlN :: Eq b => Int -> (Int -> b) -> (b -> a -> b) -> b -> f a -> b

- newtype WrappedFoldable f a = WrappedFoldable {
- getWrappedFoldable :: f a

- newtype WithoutSpeculation f a = WithoutSpeculation {
- getWithoutSpeculation :: f a

# Documentation

spec :: Eq a => a -> (a -> b) -> a -> bSource

evaluates `spec`

g f a`f g`

while forcing `a`

, if `g == a`

then `f g`

is returned. Otherwise `f a`

is evaluated.

Furthermore, if the argument has already been evaluated, we avoid sparking the parallel computation at all.

If a good guess at the value of `a`

is available, this is one way to induce parallelism in an otherwise sequential task.

However, if the guess isn't available more cheaply than the actual answer, then this saves no work and if the guess is wrong, you risk evaluating the function twice.

spec a f a = a `seq` f a

The best-case timeline looks like:

[---- f g ----] [----- a -----] [-- spec g f a --]

The worst-case timeline looks like:

[---- f g ----] [----- a -----] [---- f a ----] [------- spec g f a -----------]

Compared to the unspeculated timeline of

[---- a -----] [---- f a ----]

spec' :: Eq a => a -> (a -> b) -> a -> bSource

evaluates a function `spec'`

g f a`f `

using a cheap guess `g`

at the argument in parallel with forcing the argument.

This is one way to induce parallelism in an otherwise sequential task.
Unlike `spec`

this version
does not check to see if the argument has already been evaluated before evaluating the speculated
version. This is useful when you know `evaluated`

will always return False.

The following identity holds:

spec' a f a = a `seq` f a

Returns a guess as to whether or not a value has been evaluated. This is an impure function that relies on GHC internals and will return false negatives, but (hopefully) no false positives.

specFoldr :: (Speculative f, Eq b) => (Int -> b) -> (a -> b -> b) -> b -> f a -> bSource

Compute a right biased fold. The estimator function provides a guess at the value of the suffix

specFoldl :: (Speculative f, Eq b) => (Int -> b) -> (b -> a -> b) -> b -> f a -> bSource

Compute a left-biased fold. The estimator function provides a guess at the value of the prefix

class Foldable f => Speculative f whereSource

specFoldr1 :: Eq a => (Int -> a) -> (a -> a -> a) -> f a -> aSource

Compute a right-biased fold. The estimator function is a guess at the value of the prefix

specFoldrN :: Eq b => Int -> (Int -> b) -> (a -> b -> b) -> b -> f a -> bSource

specFoldl1 :: Eq a => (Int -> a) -> (a -> a -> a) -> f a -> aSource

Compute a left biased fold. the estimator function is a guess at the value of the prefix

specFoldlN :: Eq b => Int -> (Int -> b) -> (b -> a -> b) -> b -> f a -> bSource

Speculative [] | |

Speculative Maybe | |

Speculative IntMap | |

Speculative Set | |

Speculative Seq | |

Ix i => Speculative (Array i) | |

Speculative (Map a) | |

Foldable f => Speculative (WithoutSpeculation f) | |

Foldable f => Speculative (WrappedFoldable f) |

newtype WrappedFoldable f a Source

Functor f => Functor (WrappedFoldable f) | |

Typeable1 f => Typeable1 (WrappedFoldable f) | |

Foldable f => Foldable (WrappedFoldable f) | |

Traversable f => Traversable (WrappedFoldable f) | |

Foldable f => Speculative (WrappedFoldable f) | |

(Typeable1 f, Data (f a), Data a) => Data (WrappedFoldable f a) |

newtype WithoutSpeculation f a Source

Functor f => Functor (WithoutSpeculation f) | |

Typeable1 f => Typeable1 (WithoutSpeculation f) | |

Foldable f => Foldable (WithoutSpeculation f) | |

Traversable f => Traversable (WithoutSpeculation f) | |

Foldable f => Speculative (WithoutSpeculation f) | |

(Typeable1 f, Data (f a), Data a) => Data (WithoutSpeculation f a) |