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Document list strategies that evaluate the spine #78

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Document list strategies that evaluate the spine #78

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17 changes: 14 additions & 3 deletions Control/Parallel/Strategies.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -540,7 +540,10 @@ parTraversable strat = evalTraversable (rparWith strat)
-- Strategies for lists

-- | Evaluate each element of a list according to the given strategy.
-- Equivalent to 'evalTraversable' at the list type.
-- Equivalent to 'evalTraversable' at the list type.
--
-- __Warning:__ This strategy evaluates the spine of the list
-- and thus does not work on infinite lists.
evalList :: Strategy a -> Strategy [a]
evalList = evalTraversable
-- Alternative explicitly recursive definition:
Expand All @@ -550,14 +553,17 @@ evalList = evalTraversable
-- return (x':xs')

-- | Evaluate each element of a list in parallel according to given strategy.
-- Equivalent to 'parTraversable' at the list type.
-- Equivalent to 'parTraversable' at the list type.
--
-- __Warning:__ This strategy evaluates the spine of the list
-- and thus does not work on infinite lists.
parList :: Strategy a -> Strategy [a]
parList = parTraversable
-- Alternative definition via evalList:
-- parList strat = evalList (rparWith strat)

-- | @'evaListSplitAt' n stratPref stratSuff@ evaluates the prefix
-- (of length @n@) of a list according to @stratPref@ and its the suffix
-- (of length @n@) of a list according to @stratPref@ and the suffix
-- according to @stratSuff@.
evalListSplitAt :: Int -> Strategy [a] -> Strategy [a] -> Strategy [a]
evalListSplitAt n stratPref stratSuff xs
Expand Down Expand Up @@ -598,6 +604,9 @@ parListNth n strat = evalListNth n (rparWith strat)
--
-- This function may be replaced by a more
-- generic clustering infrastructure in the future.
--
-- __Warning:__ This strategy evaluates the spine of the list
-- and thus does not work on infinite lists.
parListChunk :: Int -> Strategy a -> Strategy [a]
parListChunk n strat
| n <= 1 = parList strat
Expand Down Expand Up @@ -630,6 +639,8 @@ evalChunk strat = \end ->
--
-- > parMap strat f = withStrategy (parList strat) . map f
--
-- __Warning:__ This function evaluates the spine of the list
-- and thus does not work on infinite lists.
parMap :: Strategy b -> (a -> b) -> [a] -> [b]
parMap strat f = (`using` parList strat) . map f

Expand Down