Strategy (core 4.6 API)

java.lang.Object
- fj.control.parallel.Strategy<A>

```
public final class Strategy<A>
extends java.lang.Object
```
Functional-style parallel evaluation strategies. A Strategy is a method of evaluating a product-1, yielding another product-1 from which the result of its evaluation can be retrieved at a later time.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`static <A> Strategy<java.util.concurrent.Callable<A>>`	`callableStrategy(Strategy<java.util.concurrent.Callable<A>> s)` Provides a normalising strategy that fully evaluates its Callable argument.
`static <A> Strategy<A>`	`completionStrategy(java.util.concurrent.CompletionService<A> s)` Provides a parallelization strategy that uses a CompletionService to control the method and degree of parallelism, and where each parallel task's completion is registered with the service.
`<B> F<B,P1<A>>`	`concurry(F<B,A> f)` Promotes a function to a concurrent function.
`<B,C> F<B,F<C,P1<A>>>`	`concurry(F2<B,C,A> f)` Promotes a function of arity-2 to a concurrent function.
`Strategy<A>`	`contramap(F<P1<A>,P1<A>> f)` Maps the given transformation across this strategy's codomain (Invariant Functor pattern).
`static <A> Effect1<java.util.concurrent.Future<A>>`	`discard()` Returns an Effect that waits for a given Future to obtain a value, discarding the value.
`Strategy<A>`	`errorStrategy(Effect1<java.lang.Error> e)` Provides an error-handling strategy.
`static <A> Strategy<A>`	`errorStrategy(Strategy<A> s, Effect1<java.lang.Error> e)` Provides an error-handling strategy.
`static <A> Strategy<A>`	`executorStrategy(java.util.concurrent.ExecutorService s)` Provides a parallelization strategy that uses an ExecutorService to control the method and degree of parallelism.
`F<P1<A>,P1<A>>`	`f()` Returns the functional representation of this Strategy, a function that evaluates a product-1.
`static <A> Strategy<A>`	`idStrategy()` Provides a strategy that performs no evaluation of its argument.
`Strategy<A>`	`map(F<P1<A>,P1<A>> f)` Maps the given transformation across this strategy's domain (Invariant Functor pattern).
`static <A> List<P1<A>>`	`mergeAll(List<java.util.concurrent.Future<A>> xs)` Waits for every Future in a list to obtain a value, and collects those values in a list.
`static <A> F<java.util.concurrent.Future<A>,P1<A>>`	`obtain()` Returns a function which returns a product-1 which waits for the given Future to obtain a value.
`static <A> P1<A>`	`obtain(java.util.concurrent.Future<A> t)` Provides a product-1 that waits for the given future to obtain a value.
`P1<A>`	`par(P1<A> a)` Apply the strategy to the given product-1.
`static <A,B> P1<Array<B>>`	`parFlatMap(Strategy<Array<B>> s, F<A,Array<B>> f, Array<A> as)` Binds the given function in parallel across the given array, using the given strategy, with a final join.
`static <A,B> P1<List<B>>`	`parFlatMap(Strategy<List<B>> s, F<A,List<B>> f, List<A> as)` Binds the given function in parallel across the given list, using the given strategy, with a final join.
`P1<List<A>>`	`parList(List<P1<A>> ps)` Evaluates a list of product-1s in parallel.
`static <A> P1<List<A>>`	`parListChunk(Strategy<List<A>> s, int chunkLength, List<P1<A>> as)` Sequentially evaluates chunks (sub-sequences) of a list in parallel.
`<B> P1<Array<A>>`	`parMap(F<B,A> f, Array<B> bs)` Maps the given function over the given array in parallel using this strategy.
`<B> P1<List<A>>`	`parMap(F<B,A> f, List<B> bs)` Maps the given function over the given list in parallel using this strategy.
`<B> Array<A>`	`parMap1(F<B,A> f, Array<B> bs)` A strict version of parMap over arrays.
`<B> List<A>`	`parMap1(F<B,A> f, List<B> bs)` A strict version of parMap over lists.
`<B> F<F<B,A>,F<Array<B>,P1<Array<A>>>>`	`parMapArray()` First-class version of parMap on arrays.
`<B> F<Array<B>,P1<Array<A>>>`	`parMapArray(F<B,A> f)` Promotes a function to a parallel function on arrays using this strategy.
`<B> F<F<B,A>,F<Array<B>,Array<A>>>`	`parMapArray1()` First-class version of parMap1 on arrays (parallel array functor).
`<B> F<F<B,A>,F<List<B>,P1<List<A>>>>`	`parMapList()` First-class version of parMap on lists.
`<B> F<List<B>,P1<List<A>>>`	`parMapList(F<B,A> f)` Promotes a function to a parallel function on lists using this strategy.
`<B> F<F<B,A>,F<List<B>,List<A>>>`	`parMapList1()` First-class version of parMap1 on lists (parallel list functor).
`<B,C> F2<Array<B>,Array<C>,P1<Array<A>>>`	`parZipArrayWith(F2<B,C,A> f)` Lifts a given function of arity-2 so that it zips together two arrays in parallel, using this strategy, calling the function once for each corresponding pair in the arrays, position-wise.
`<B,C> F2<List<B>,List<C>,P1<List<A>>>`	`parZipListWith(F2<B,C,A> f)` Lifts a given function of arity-2 so that it zips together two lists in parallel, using this strategy, calling the function once for each corresponding pair in the lists, position-wise.
`<B,C> P1<Array<A>>`	`parZipWith(F2<B,C,A> f, Array<B> bs, Array<C> cs)` Zips together two arrays in parallel using a given function, with this strategy.
`<B,C> P1<List<A>>`	`parZipWith(F2<B,C,A> f, List<B> bs, List<C> cs)` Zips together two lists in parallel using a given function, with this strategy.
`static <A> Strategy<A>`	`seqStrategy()` Provides a strategy that performs sequential (non-concurrent) evaluation of its argument.
`static <A> Strategy<A>`	`simpleThreadStrategy()` Provides a simple parallelization strategy that creates, and discards, a new thread for every evaluation.
`static <A> Strategy<A>`	`strategy(F<P1<A>,P1<A>> f)` Constructs a strategy from the given evaluation function.
`<B> Strategy<B>`	`xmap(F<P1<A>,P1<B>> f, F<P1<B>,P1<A>> g)` Maps the given bijective transformation across this strategy (Exponential Functor pattern).

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
 - f
```
public F<P1<A>,P1<A>> f()
```
 Returns the functional representation of this Strategy, a function that evaluates a product-1.
 
 Returns:
 
 The function representing this strategy, which evaluates a product-1.
 - strategy
```
public static <A> Strategy<A> strategy(F<P1<A>,P1<A>> f)
```
 Constructs a strategy from the given evaluation function.
 
 Parameters:
 
 f - The execution function for the strategy
 
 Returns:
 
 A strategy that uses the given function to evaluate product-1s.
 - par
```
public P1<A> par(P1<A> a)
```
 Apply the strategy to the given product-1.
 
 Parameters:
 
 a - A P1 to evaluate according to this strategy.
 
 Returns:
 
 A P1 that yields the value from calling the given product-1.
 - concurry
```
public  F<B,P1<A>> concurry(F<B,A> f)
```
 Promotes a function to a concurrent function.
 
 Parameters:
 
 f - A function to promote to a concurrent function.
 
 Returns:
 
 A function that executes concurrently when called, yielding a Future value.
 - concurry
```
public <B,C> F<B,F<C,P1<A>>> concurry(F2<B,C,A> f)
```
 Promotes a function of arity-2 to a concurrent function.
 
 Parameters:
 
 f - The function to promote to a concurrent function.
 
 Returns:
 
 A function that executes concurrently when called, yielding a product-1 that returns the value.
 - mergeAll
```
public static <A> List<P1<A>> mergeAll(List<java.util.concurrent.Future<A>> xs)
```
 Waits for every Future in a list to obtain a value, and collects those values in a list.
 
 Parameters:
 
 xs - The list of Futures from which to get values.
 
 Returns:
 
 A list of values extracted from the Futures in the argument list.
 - parList
```
public P1<List<A>> parList(List<P1<A>> ps)
```
 Evaluates a list of product-1s in parallel.
 
 Parameters:
 
 ps - A list to evaluate in parallel.
 
 Returns:
 
 A list of the values of the product-1s in the argument.
 - parMap
```
public  P1<List<A>> parMap(F<B,A> f,
 List bs)
```
 Maps the given function over the given list in parallel using this strategy.
 
 Parameters:
 
 f - A function to map over the given list in parallel.
 
 bs - A list over which to map the given function in parallel.
 
 Returns:
 
 A product-1 that returns the list with all of its elements transformed by the given function.
 - parMap
```
public  P1<Array<A>> parMap(F<B,A> f,
 Array bs)
```
 Maps the given function over the given array in parallel using this strategy.
 
 Parameters:
 
 f - A function to map over the given array in parallel.
 
 bs - An array over which to map the given function in parallel.
 
 Returns:
 
 A product-1 that returns the array with all of its elements transformed by the given function.
 - parMap1
```
public  List<A> parMap1(F<B,A> f,
 List bs)
```
 A strict version of parMap over lists. Maps the given function over the given list in parallel using this strategy, blocking the current thread until all values have been obtained.
 
 Parameters:
 
 f - A function to map over the given list in parallel.
 
 bs - A list over which to map the given function in parallel.
 
 Returns:
 
 A list with all of its elements transformed by the given function.
 - parMap1
```
public  Array<A> parMap1(F<B,A> f,
 Array bs)
```
 A strict version of parMap over arrays. Maps the given function over the given arrays in parallel using this strategy, blocking the current thread until all values have been obtained.
 
 Parameters:
 
 f - A function to map over the given array in parallel.
 
 bs - An array over which to map the given function in parallel.
 
 Returns:
 
 An array with all of its elements transformed by the given function.
 - parMapList
```
public  F<List,P1<List<A>>> parMapList(F<B,A> f)
```
 Promotes a function to a parallel function on lists using this strategy.
 
 Parameters:
 
 f - A function to transform into a parallel function on lists.
 
 Returns:
 
 The function transformed into a parallel function on lists.
 - parMapList
```
public  F<F<B,A>,F<List,P1<List<A>>>> parMapList()
```
 First-class version of parMap on lists.
 
 Returns:
 
 A function that promotes another function to a parallel function on lists.
 - parMapList1
```
public  F<F<B,A>,F<List,List<A>>> parMapList1()
```
 First-class version of parMap1 on lists (parallel list functor).
 
 Returns:
 
 A function that promotes another function to a blocking parallel function on lists.
 - parMapArray
```
public  F<Array,P1<Array<A>>> parMapArray(F<B,A> f)
```
 Promotes a function to a parallel function on arrays using this strategy.
 
 Parameters:
 
 f - A function to transform into a parallel function on arrays.
 
 Returns:
 
 The function transformed into a parallel function on arrays.
 - parMapArray
```
public  F<F<B,A>,F<Array,P1<Array<A>>>> parMapArray()
```
 First-class version of parMap on arrays.
 
 Returns:
 
 A function that promotes another function to a parallel function on arrays.
 - parMapArray1
```
public  F<F<B,A>,F<Array,Array<A>>> parMapArray1()
```
 First-class version of parMap1 on arrays (parallel array functor).
 
 Returns:
 
 A function that promotes another function to a blocking parallel function on arrays.
 - parFlatMap
```
public static <A,B> P1<List> parFlatMap(Strategy<List> s,
 F<A,List> f,
 List<A> as)
```
 Binds the given function in parallel across the given list, using the given strategy, with a final join.
 
 Parameters:
 
 s - The strategy to use for parallelization.
 
 f - The function to bind across the given list.
 
 as - The list across which to bind the given function.
 
 Returns:
 
 A P1 containing the result of the parallel map operation after the final join.
 - parFlatMap
```
public static <A,B> P1<Array> parFlatMap(Strategy<Array> s,
 F<A,Array> f,
 Array<A> as)
```
 Binds the given function in parallel across the given array, using the given strategy, with a final join.
 
 Parameters:
 
 s - The strategy to use for parallelization.
 
 f - The function to bind across the given array.
 
 as - The array across which to bind the given function.
 
 Returns:
 
 A P1 containing the result of the parallel map operation after the final join.
 - parListChunk
```
public static <A> P1<List<A>> parListChunk(Strategy<List<A>> s,
 int chunkLength,
 List<P1<A>> as)
```
 Sequentially evaluates chunks (sub-sequences) of a list in parallel. Splits the list into chunks, evaluating the chunks simultaneously, but each chunk as a sequence.
 
 Parameters:
 
 s - The strategy to use for parallelization.
 
 chunkLength - The length of each sequence.
 
 as - The list to evaluate in parallel chunks.
 
 Returns:
 
 A product-1 containing the list of results extracted from the given list of product-1s.
 - parZipWith
```
public <B,C> P1<List<A>> parZipWith(F2<B,C,A> f,
 List bs,
 List<C> cs)
```
 Zips together two lists in parallel using a given function, with this strategy. Calls the given function once for each corresponding pair in the lists, position-wise, passing elements from the first list to the first argument of the function, and elements from the second list to the second argument of the function, yielding a list of the results. If the lists are not of the same length, the remaining elements of the longer list are ignored.
 
 Parameters:
 
 f - The function of arity-2 with which to zip.
 
 bs - A list to zip with the given function.
 
 cs - A list to zip with the given function.
 
 Returns:
 
 The list of the results of calling the given function on corresponding elements of the given lists.
 - parZipWith
```
public <B,C> P1<Array<A>> parZipWith(F2<B,C,A> f,
 Array bs,
 Array<C> cs)
```
 Zips together two arrays in parallel using a given function, with this strategy. Calls the given function once for each corresponding pair in the arrays, position-wise, passing elements from the first array to the first argument of the function, and elements from the second array to the second argument of the function, yielding a array of the results. If the arrays are not of the same length, the remaining elements of the longer array are ignored.
 
 Parameters:
 
 f - The function of arity-2 with which to zip.
 
 bs - A array to zip with the given function.
 
 cs - A array to zip with the given function.
 
 Returns:
 
 The array of the results of calling the given function on corresponding elements of the given arrays.
 - parZipListWith
```
public <B,C> F2<List,List<C>,P1<List<A>>> parZipListWith(F2<B,C,A> f)
```
 Lifts a given function of arity-2 so that it zips together two lists in parallel, using this strategy, calling the function once for each corresponding pair in the lists, position-wise.
 
 Parameters:
 
 f - The function of arity-2 with which to zip.
 
 Returns:
 
 A transformation that zips two lists using the argument function, in parallel.
 - parZipArrayWith
```
public <B,C> F2<Array,Array<C>,P1<Array<A>>> parZipArrayWith(F2<B,C,A> f)
```
 Lifts a given function of arity-2 so that it zips together two arrays in parallel, using this strategy, calling the function once for each corresponding pair in the arrays, position-wise.
 
 Parameters:
 
 f - The function of arity-2 with which to zip.
 
 Returns:
 
 A transformation that zips two arrays using the argument function, in parallel.
 - obtain
```
public static <A> F<java.util.concurrent.Future<A>,P1<A>> obtain()
```
 Returns a function which returns a product-1 which waits for the given Future to obtain a value.
 
 Returns:
 
 A function which, given a Future, yields a product-1 that waits for it.
 - obtain
```
public static <A> P1<A> obtain(java.util.concurrent.Future<A> t)
```
 Provides a product-1 that waits for the given future to obtain a value.
 
 Parameters:
 
 t - A Future for which to wait.
 
 Returns:
 
 A product-1 that waits for the given future to obtain a value.
 - discard
```
public static <A> Effect1<java.util.concurrent.Future<A>> discard()
```
 Returns an Effect that waits for a given Future to obtain a value, discarding the value.
 
 Returns:
 
 An effect, which, given a Future, waits for it to obtain a value, discarding the value.
 - simpleThreadStrategy
```
public static <A> Strategy<A> simpleThreadStrategy()
```
 Provides a simple parallelization strategy that creates, and discards, a new thread for every evaluation.
 
 Returns:
 
 a simple parallelization strategy that creates, and discards, a new thread for every evaluation.
 - executorStrategy
```
public static <A> Strategy<A> executorStrategy(java.util.concurrent.ExecutorService s)
```
 Provides a parallelization strategy that uses an ExecutorService to control the method and degree of parallelism.
 
 Parameters:
 
 s - The ExecutorService to use for scheduling evaluations.
 
 Returns:
 
 A Strategy that uses the provided ExecutorService to control the method and degree of parallelism.
 - completionStrategy
```
public static <A> Strategy<A> completionStrategy(java.util.concurrent.CompletionService<A> s)
```
 Provides a parallelization strategy that uses a CompletionService to control the method and degree of parallelism, and where each parallel task's completion is registered with the service.
 
 Parameters:
 
 s - The CompletionService to use for scheduling evaluations and detect their completion.
 
 Returns:
 
 A Strategy that uses the provided CompletionService to control the method and degree of parallelism, and notifies the service of task completion.
 - seqStrategy
```
public static <A> Strategy<A> seqStrategy()
```
 Provides a strategy that performs sequential (non-concurrent) evaluation of its argument.
 
 Returns:
 
 A strategy that performs sequential (non-concurrent) evaluation of its argument.
 - idStrategy
```
public static <A> Strategy<A> idStrategy()
```
 Provides a strategy that performs no evaluation of its argument.
 
 Returns:
 
 A strategy that performs no evaluation of its argument.
 - xmap
```
public  Strategy xmap(F<P1<A>,P1> f,
 F<P1,P1<A>> g)
```
 Maps the given bijective transformation across this strategy (Exponential Functor pattern).
 
 Parameters:
 
 f - A transformation from this strategy's codomain to the resulting strategy's codomain.
 
 g - A transformation from the resulting strategy's domain to this strategy's domain.
 
 Returns:
 
 A new strategy that maps to this strategy and back again.
 - map
```
public Strategy<A> map(F<P1<A>,P1<A>> f)
```
 Maps the given transformation across this strategy's domain (Invariant Functor pattern).
 
 Parameters:
 
 f - A transformation from this strategy's codomain to the resulting strategy's codomain.
 
 Returns:
 
 A new strategy that applies the given transformation after each application of this strategy.
 - contramap
```
public Strategy<A> contramap(F<P1<A>,P1<A>> f)
```
 Maps the given transformation across this strategy's codomain (Invariant Functor pattern).
 
 Parameters:
 
 f - A transformation from the resulting strategy's domain to this strategy's domain.
 
 Returns:
 
 A new strategy that applies the given transformation before each application of this strategy.
 - errorStrategy
```
public Strategy<A> errorStrategy(Effect1<java.lang.Error> e)
```
 Provides an error-handling strategy. Captures any uncaught runtime errors encountered by this strategy and applies the given side-effect to them.
 
 Parameters:
 
 e - The effect that should handle errors.
 
 Returns:
 
 A strategy that captures any runtime errors with a side-effect.
 - errorStrategy
```
public static <A> Strategy<A> errorStrategy(Strategy<A> s,
 Effect1<java.lang.Error> e)
```
 Provides an error-handling strategy. Captures any uncaught runtime errors encountered by the given strategy and applies the given side-effect to them.
 
 Parameters:
 
 s - The strategy to equip with an error-handling effect.
 
 e - The effect that should handle errors.
 
 Returns:
 
 A strategy that captures any runtime errors with a side-effect.
 - callableStrategy
```
public static <A> Strategy<java.util.concurrent.Callable<A>> callableStrategy(Strategy<java.util.concurrent.Callable<A>> s)
```
 Provides a normalising strategy that fully evaluates its Callable argument.
 
 Parameters:
 
 s - A non-normalising strategy to use for the evaluation.
 
 Returns:
 
 A new strategy that fully evaluates Callables, using the given strategy.

Class Strategy<A>

Method Summary

Methods inherited from class java.lang.Object

Method Detail

f

strategy

par

concurry

concurry

mergeAll

parList

parMap

parMap

parMap1

parMap1

parMapList

parMapList

parMapList1

parMapArray

parMapArray

parMapArray1

parFlatMap

parFlatMap

parListChunk

parZipWith

parZipWith

parZipListWith

parZipArrayWith

obtain

obtain

discard

simpleThreadStrategy

executorStrategy

completionStrategy

seqStrategy

idStrategy

xmap

map

contramap

errorStrategy

errorStrategy

callableStrategy