Control.Concurrent.SCC.Configurable

This module exports the entire SCC library except for low-level modules Control.Concurrent.SCC.Streams and Control.Concurrent.SCC.Types. The exported combinators can be configured to run their components sequentially or in parallel depending on the available resources.

Configurable component types

type PerformerComponent m r = Component (Performer m r)

A component that performs a computation with no inputs nor outputs is a PerformerComponent.

type ConsumerComponent m x r = Component (Consumer m x r)

A component that consumes values from a Source is called ConsumerComponent.

type ProducerComponent m x r = Component (Producer m x r)

A component that produces values and puts them into a Sink is called ProducerComponent.

type TransducerComponent m x y = Component (Transducer m x y)

The TransducerComponent type represents computations that transform a data stream.

type SplitterComponent m x = Component (Splitter m x)

The SplitterComponent type represents computations that distribute data acording to some criteria. A splitter should distribute only the original input data, and feed it into the sinks in the same order it has been read from the source. If the two 'Sink c x' arguments of a splitter are the same, the splitter must act as an identity transform.

ioCost :: Int

The constant cost of each I/O-performing component.

Coercible class

coerce :: (Monad m, Coercible x y) => TransducerComponent m x y

A TransducerComponent that converts a stream of one type to another.

adaptConsumer :: (Monad m, Monoid x, Monoid y, Coercible x y) => ConsumerComponent m y r -> ConsumerComponent m x r

Adjusts the argument consumer to consume the stream of a data type coercible to the type it was meant to consume.

adaptProducer :: (Monad m, Monoid x, Monoid y, Coercible x y) => ProducerComponent m x r -> ProducerComponent m y r

Adjusts the argument producer to produce the stream of a data type coercible from the type it was meant to produce.

Splitter isomorphism

adaptSplitter :: (Monad m, Monoid x, Monoid y, Coercible x y, Coercible y x) => SplitterComponent m x -> SplitterComponent m y

Adjusts the argument splitter to split the stream of a data type isomorphic to the type it was meant to split.

I/O components

I/O producers

fromStdIn :: ProducerComponent IO Text ()

ProducerComponent fromStdIn feeds the given sink from the standard input.

fromFile :: String -> ProducerComponent IO Text ()

ProducerComponent fromFile opens the named file and feeds the given sink from its contents.

fromHandle :: Handle -> ProducerComponent IO Text ()

ProducerComponent fromHandle feeds the given sink from the open file handle.

I/O consumers

toStdOut :: ConsumerComponent IO Text ()

ConsumerComponent toStdOut copies the given source into the standard output.

toFile :: String -> ConsumerComponent IO Text ()

ConsumerComponent toFile opens the named file and copies the given source into it.

appendFile :: String -> ConsumerComponent IO Text ()

ConsumerComponent appendFile opens the name file and appends the given source to it.

toHandle :: Handle -> ConsumerComponent IO Text ()

ConsumerComponent toHandle copies the given source into the open file handle.

Generic components

produceFrom :: (Monad m, MonoidNull x) => x -> ProducerComponent m x ()

produceFrom produces the contents of the given argument.

Generic consumers

consumeInto :: (Monad m, Monoid x) => ConsumerComponent m x x

ConsumerComponent consumeInto collects the given source into the return value.

suppress :: Monad m => ConsumerComponent m x ()

The suppress consumer suppresses all input it receives. It is equivalent to substitute []

erroneous :: (Monad m, MonoidNull x) => String -> ConsumerComponent m x ()

The erroneous consumer reports an error if any input reaches it.

Generic transducers

id :: (Monad m, Monoid x) => TransducerComponent m x x

TransducerComponent id passes its input through unmodified.

unparse :: (Monad m, Monoid x) => TransducerComponent m [Markup b x] x

TransducerComponent unparse removes all markup from its input and passes the content through.

parse :: (Monad m, Monoid x) => ParserComponent m x y

TransducerComponent parse prepares input content for subsequent parsing.

lowercase :: Monad m => TransducerComponent m String String

The lowercase transforms all uppercase letters in the input to lowercase, leaving the rest unchanged.

uppercase :: Monad m => TransducerComponent m String String

The uppercase transforms all lowercase letters in the input to uppercase, leaving the rest unchanged.

count :: (Monad m, FactorialMonoid x) => TransducerComponent m x [Integer]

The count transducer counts all its input values and outputs the final tally.

toString :: (Monad m, Show x) => TransducerComponent m [x] [String]

Converts each input value x to show x.

parseSubstring :: (Monad m, Eq x, LeftCancellativeMonoid x, FactorialMonoid x) => x -> ParserComponent m x OccurenceTag

Performs the same task as the substring splitter, but instead of splitting it outputs the input as Markup x OccurenceTag in order to distinguish overlapping strings.

List stream transducers

group :: (Monad m, Monoid x) => TransducerComponent m x [x]

TransducerComponent group collects all its input into a single list item.

concatenate :: (Monad m, Monoid x) => TransducerComponent m [x] x

TransducerComponent concatenate flattens the input stream of lists of values into the output stream of values.

concatSeparate :: (Monad m, MonoidNull x) => x -> TransducerComponent m [x] x

Same as concatenate except it inserts the given separator list between every two input lists.

Generic splitters

everything :: Monad m => SplitterComponent m x

SplitterComponent everything feeds its entire input into its true sink.

nothing :: (Monad m, Monoid x) => SplitterComponent m x

SplitterComponent nothing feeds its entire input into its false sink.

marked :: (Monad m, Eq y) => SplitterComponent m [Markup y x]

SplitterComponent marked passes all marked-up input sections to its true sink, and all unmarked input to its false sink.

markedContent :: (Monad m, Eq y) => SplitterComponent m [Markup y x]

SplitterComponent markedContent passes the content of all marked-up input sections to its true sink, while the outermost tags and all unmarked input go to its false sink.

markedWith :: (Monad m, Eq y) => (y -> Bool) -> SplitterComponent m [Markup y x]

SplitterComponent markedWith passes input sections marked-up with the appropriate tag to its true sink, and the rest of the input to its false sink. The argument select determines if the tag is appropriate.

contentMarkedWith :: (Monad m, Eq y) => (y -> Bool) -> SplitterComponent m [Markup y x]

SplitterComponent contentMarkedWith passes the content of input sections marked-up with the appropriate tag to its true sink, and the rest of the input to its false sink. The argument select determines if the tag is appropriate.

one :: (Monad m, FactorialMonoid x) => SplitterComponent m x

SplitterComponent one feeds all input values to its true sink, treating every value as a separate section.

substring :: (Monad m, Eq x, LeftCancellativeMonoid x, FactorialMonoid x) => x -> SplitterComponent m x

SplitterComponent substring feeds to its true sink all input parts that match the contents of the given list argument. If two overlapping parts of the input both match the argument, both are sent to true and each is preceded by an empty chunk on false.

Character stream components

whitespace :: Monad m => SplitterComponent m String

SplitterComponent whitespace feeds all white-space characters into its true sink, all others into false.

letters :: Monad m => SplitterComponent m String

SplitterComponent letters feeds all alphabetical characters into its true sink, all other characters into | false.

digits :: Monad m => SplitterComponent m String

SplitterComponent digits feeds all digits into its true sink, all other characters into false.

nonEmptyLine :: Monad m => SplitterComponent m String

SplitterComponent nonEmptyLine feeds line-ends into its false sink, and all other characters into true.

line :: Monad m => SplitterComponent m String

The sectioning splitter line feeds line-ends into its false sink, and line contents into true. A single line-end can be formed by any of the character sequences "\n", "\r", "\r\n", or "\n\r".

Consumer, producer, and transducer combinators

consumeBy :: Monad m => ConsumerComponent m x r -> TransducerComponent m x y

Converts a ConsumerComponent into a TransducerComponent with no output.

(>->) :: (MonadParallel m, PipeableComponentPair m w c1 c2 c3) => Component c1 -> Component c2 -> Component c3

Class PipeableComponentPair applies to any two components that can be combined into a third component with the following properties:

• The input of the result, if any, becomes the input of the first component.
• The output produced by the first child component is consumed by the second child component.
• The result output, if any, is the output of the second component.

join :: (MonadParallel m, JoinableComponentPair t1 t2 t3 m x y c1 c2 c3) => Component c1 -> Component c2 -> Component c3

Class JoinableComponentPair applies to any two components that can be combined into a third component with the following properties:

• if both argument components consume input, the input of the combined component gets distributed to both components in parallel,
• if both argument components produce output, the output of the combined component is a concatenation of the complete output from the first component followed by the complete output of the second component, and

The join combinator may apply the components in any order.

sequence :: JoinableComponentPair t1 t2 t3 m x y c1 c2 c3 => Component c1 -> Component c2 -> Component c3

The sequence combinator makes sure its first argument has completed before using the second one.

prepend :: Monad m => ProducerComponent m x r -> TransducerComponent m x x

Combinator prepend converts the given producer to transducer that passes all its input through unmodified, except | for prepending the output of the argument producer to it. | prepend prefix = join (substitute prefix) asis

append :: Monad m => ProducerComponent m x r -> TransducerComponent m x x

Combinator append converts the given producer to transducer that passes all its input through unmodified, finally | appending to it the output of the argument producer. | append suffix = join asis (substitute suffix)

substitute :: (Monad m, Monoid x) => ProducerComponent m y r -> TransducerComponent m x y

The substitute combinator converts its argument producer to a transducer that produces the same output, while | consuming its entire input and ignoring it.

Splitter combinators

snot :: (Monad m, Monoid x) => SplitterComponent m x -> SplitterComponent m x

The snot (streaming not) combinator simply reverses the outputs of the argument splitter. In other words, data that the argument splitter sends to its true sink goes to the false sink of the result, and vice versa.

Pseudo-logic flow combinators

(>&) :: (MonadParallel m, Monoid x) => SplitterComponent m x -> SplitterComponent m x -> SplitterComponent m x

The >& combinator sends the true sink output of its left operand to the input of its right operand for further splitting. Both operands' false sinks are connected to the false sink of the combined splitter, but any input value to reach the true sink of the combined component data must be deemed true by both splitters.

(>|) :: (MonadParallel m, Monoid x) => SplitterComponent m x -> SplitterComponent m x -> SplitterComponent m x

A >| combinator's input value can reach its false sink only by going through both argument splitters' false sinks.

Zipping logic combinators

(&&) :: (MonadParallel m, FactorialMonoid x) => SplitterComponent m x -> SplitterComponent m x -> SplitterComponent m x

Combinator && is a pairwise logical conjunction of two splitters run in parallel on the same input.

(||) :: (MonadParallel m, FactorialMonoid x) => SplitterComponent m x -> SplitterComponent m x -> SplitterComponent m x

Combinator || is a pairwise logical disjunction of two splitters run in parallel on the same input.

Flow-control combinators

Recursive

while :: (MonadParallel m, MonoidNull x) => TransducerComponent m x x -> SplitterComponent m x -> TransducerComponent m x x

The recursive combinator while feeds the true sink of the argument splitter back to itself, modified by the argument transducer. Data fed to the splitter's false sink is passed on unmodified.

nestedIn :: (MonadParallel m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x -> SplitterComponent m x

The recursive combinator nestedIn combines two splitters into a mutually recursive loop acting as a single splitter. The true sink of one of the argument splitters and false sink of the other become the true and false sinks of the loop. The other two sinks are bound to the other splitter's source. The use of nestedIn makes sense only on hierarchically structured streams. If we gave it some input containing a flat sequence of values, and assuming both component splitters are deterministic and stateless, an input value would either not loop at all or it would loop forever.

Section-based combinators

foreach :: (MonadParallel m, MonoidNull x, Branching c m x ()) => SplitterComponent m x -> Component c -> Component c -> Component c

The foreach combinator is similar to the combinator ifs in that it combines a splitter and two transducers into another transducer. However, in this case the transducers are re-instantiated for each consecutive portion of the input as the splitter chunks it up. Each contiguous portion of the input that the splitter sends to one of its two sinks gets transducered through the appropriate argument transducer as that transducer's whole input. As soon as the contiguous portion is finished, the transducer gets terminated.

having :: (MonadParallel m, MonoidNull x, MonoidNull y, Coercible x y) => SplitterComponent m x -> SplitterComponent m y -> SplitterComponent m x

The having combinator combines two pure splitters into a pure splitter. One splitter is used to chunk the input into contiguous portions. Its false sink is routed directly to the false sink of the combined splitter. The second splitter is instantiated and run on each portion of the input that goes to first splitter's true sink. If the second splitter sends any output at all to its true sink, the whole input portion is passed on to the true sink of the combined splitter, otherwise it goes to its false sink.

havingOnly :: (MonadParallel m, MonoidNull x, MonoidNull y, Coercible x y) => SplitterComponent m x -> SplitterComponent m y -> SplitterComponent m x

The havingOnly combinator is analogous to the having combinator, but it succeeds and passes each chunk of the input to its true sink only if the second splitter sends no part of it to its false sink.

followedBy :: (MonadParallel m, FactorialMonoid x) => SplitterComponent m x -> SplitterComponent m x -> SplitterComponent m x

Combinator followedBy treats its argument SplitterComponents as patterns components and returns a SplitterComponent that matches their concatenation. A section of input is considered true by the result iff its prefix is considered true by argument s1 and the rest of the section is considered true by s2. The splitter s2 is started anew after every section split to true sink by s1.

even :: (Monad m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x

The even combinator takes every input section that its argument splitter deems true, and feeds even ones into its true sink. The odd sections and parts of input that are false according to its argument splitter are fed to even splitter's false sink.

first and its variants

first :: (Monad m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x

The result of combinator first behaves the same as the argument splitter up to and including the first portion of the input which goes into the argument's true sink. All input following the first true portion goes into the false sink.

uptoFirst :: (Monad m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x

The result of combinator uptoFirst takes all input up to and including the first portion of the input which goes into the argument's true sink and feeds it to the result splitter's true sink. All the rest of the input goes into the false sink. The only difference between first and uptoFirst combinators is in where they direct the false portion of the input preceding the first true part.

prefix :: (Monad m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x

The prefix combinator feeds its true sink only the prefix of the input that its argument feeds to its true sink. All the rest of the input is dumped into the false sink of the result.

last and its variants

last :: (Monad m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x

The result of the combinator last is a splitter which directs all input to its false sink, up to the last portion of the input which goes to its argument's true sink. That portion of the input is the only one that goes to the resulting component's true sink. The splitter returned by the combinator last has to buffer the previous two portions of its input, because it cannot know if a true portion of the input is the last one until it sees the end of the input or another portion succeeding the previous one.

lastAndAfter :: (Monad m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x

The result of the combinator lastAndAfter is a splitter which directs all input to its false sink, up to the last portion of the input which goes to its argument's true sink. That portion and the remainder of the input is fed to the resulting component's true sink. The difference between last and lastAndAfter combinators is where they feed the false portion of the input, if any, remaining after the last true part.

suffix :: (Monad m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x

The suffix combinator feeds its true sink only the suffix of the input that its argument feeds to its true sink. All the rest of the input is dumped into the false sink of the result.

positional splitters

startOf :: (Monad m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x

SplitterComponent startOf issues an empty true section at the beginning of every section considered true by its argument splitter, otherwise the entire input goes into its false sink.

endOf :: (Monad m, MonoidNull x) => SplitterComponent m x -> SplitterComponent m x

SplitterComponent endOf issues an empty true section at the end of every section considered true by its argument splitter, otherwise the entire input goes into its false sink.

(...) :: (MonadParallel m, FactorialMonoid x) => SplitterComponent m x -> SplitterComponent m x -> SplitterComponent m x

Combinator ... tracks the running balance of difference between the number of preceding starts of sections considered true according to its first argument and the ones according to its second argument. The combinator passes to true all input values for which the difference balance is positive. This combinator is typically used with startOf and endOf in order to count entire input sections and ignore their lengths.

Parser support

parseRegions :: (Monad m, MonoidNull x) => SplitterComponent m x -> ParserComponent m x ()

Converts a splitter into a parser.

Parsing XML

xmlTokens :: Monad m => SplitterComponent m Text

This splitter splits XML markup from data content. It is used by parseXMLTokens.

xmlParseTokens :: MonadParallel m => TransducerComponent m Text [Markup XMLToken Text]

The XML token parser. This parser converts plain text to parsed text, which is a precondition for using the remaining XML components.

XML splitters

xmlElement :: Monad m => SplitterComponent m [Markup XMLToken Text]

Splits all top-level elements with all their content to true, all other input to false.

xmlElementContent :: Monad m => SplitterComponent m [Markup XMLToken Text]

Splits the content of all top-level elements to true, their tags and intervening input to false.

xmlElementHavingTagWith :: MonadParallel m => SplitterComponent m [Markup XMLToken Text] -> SplitterComponent m [Markup XMLToken Text]

Similiar to (having element), except it runs the argument splitter only on each element's start tag, not on the entire element with its content.

xmlAttribute :: Monad m => SplitterComponent m [Markup XMLToken Text]

Splits every attribute specification to true, everything else to false.

xmlElementName :: Monad m => SplitterComponent m [Markup XMLToken Text]

Splits every element name, including the names of nested elements and names in end tags, to true, all the rest of input to false.

xmlAttributeName :: Monad m => SplitterComponent m [Markup XMLToken Text]

Splits every attribute name to true, all the rest of input to false.

xmlAttributeValue :: Monad m => SplitterComponent m [Markup XMLToken Text]

Splits every attribute value, excluding the quote delimiters, to true, all the rest of input to false.

The Component type

data Component c

A Component carries a value and metadata about the value. It can be configured to use a specific number of threads.

Constructors

Component

Fields

• name :: String

  Readable component name.

• subComponents :: [AnyComponent]

  Returns the list of all children components.

• maxUsableThreads :: Int

  Returns the maximum number of threads that can be used by the component.

• usingThreads :: Int -> Component c

  Configures the component to use the specified number of threads. This function affects usedThreads, cost, and subComponents methods of the result, while name and maxUsableThreads remain the same.

• usedThreads :: Int

  The number of threads that the component is configured to use. The default number is usually 1.

• cost :: Int

  The cost of using the component as configured. The cost is a rough approximation of time it would take to do the job given the usedThreads.

• with :: c

  The content.

Instances

Functor Component

Methods

fmap :: (a -> b) -> Component a -> Component b

(<$) :: a -> Component b -> Component a

Utility functions

showComponentTree :: forall c. Component c -> String

Show details of the given component's configuration.

Constructors

atomic :: String -> Int -> c -> Component c

Function atomic takes the component name and its cost creates a single-threaded component with no subcomponents.

lift

Arguments

:: Int

combinator cost

-> String

name

-> (c1 -> c2)

combinator

-> Component c1

-> Component c2

Applies a unary combinator to the component payload. The resulting component has the original one as its subComponents, and its cost is the sum of the original component's cost and the combinator cost.

liftParallelPair :: String -> (Bool -> c1 -> c2 -> c3) -> Component c1 -> Component c2 -> Component c3

Combines two components into one, applying combinator to their contents. The combinator takes a flag denoting if its arguments should run in parallel. The cost and usingThreads of the result assume the parallel execution of the argument components.

liftSequentialPair :: String -> (c1 -> c2 -> c3) -> Component c1 -> Component c2 -> Component c3

Combines two components into one, applying combinator to their contents. The cost and usingThreads of the result assume the sequential execution of the argument components.

parallelRouterAndBranches :: String -> (Bool -> c1 -> c2 -> c3 -> c4) -> Component c1 -> Component c2 -> Component c3 -> Component c4

Combines three components into one. The first component runs in parallel with the latter two, which are considered alternative to each other.

recursiveComponentTree :: forall c1 c2. String -> (Bool -> c1 -> c2 -> c2) -> Component c1 -> Component c2

Builds a tree of recursive components. The combinator takes a list of pairs of a boolean flag denoting whether the level should be run in parallel and the value.

expandXMLEntity :: String -> String

Converts an XML entity name into the text value it represents: expandXMLEntity "lt" = "<".