Control.Concurrent.SCC.Parallel

This module exports the entire SCC library except for low-level modules Control.Concurrent.SCC.Streams and Control.Concurrent.SCC.Types. The exported combinators run their components in parallel.

Coercible class

class Coercible x y where

Two streams of Coercible types can be unambigously converted one to another.

Methods

coerce :: Monad m => Transducer m x y

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

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

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

Instances

Coercible String Text

Coercible x x

Coercible Text String

Monoid x => Coercible [x] x

(Monoid x, Monoid y, Coercible x y) => Coercible [Markup b x] y

Coercible [Char] [Text]

Coercible [x] [y] => Coercible [[x]] [y]

Coercible [Text] [Char]

Coercible [x] [y] => Coercible [Markup b x] [y]

Splitter isomorphism

adaptSplitter :: forall m x y b. (Monad m, Monoid x, Monoid y, Coercible x y, Coercible y x) => Splitter m x -> Splitter 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

fromFile :: String -> Producer IO Text ()

Reads the named file and feeds the given sink from its contents.

fromHandle :: Handle -> Producer IO Text ()

Feeds the given sink from the open text file handle.

fromStdIn :: Producer IO Text ()

Producer fromStdIn feeds the given sink from the standard input.

fromBinaryHandle :: Handle -> Int -> Producer IO ByteString ()

Feeds the given sink from the open binary file handle. The argument chunkSize determines the size of the chunks read from the handle.

I/O consumers

appendFile :: String -> Consumer IO Text ()

Appends the given source to the named text file.

toFile :: String -> Consumer IO Text ()

Creates the named text file and writes the entire given source to it.

toHandle :: Handle -> Consumer IO Text ()

Copies the given source into the open text file handle.

toStdOut :: Consumer IO Text ()

Consumer toStdOut copies the given source into the standard output.

toBinaryHandle :: Handle -> Consumer IO ByteString ()

Copies the given source into the open binary file handle.

Generic components

produceFrom :: forall m x. (Monad m, MonoidNull x) => x -> Producer m x ()

Produces the contents of the given argument.

Generic consumers

suppress :: forall m x. Monad m => Consumer m x ()

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

erroneous :: forall m x. (Monad m, MonoidNull x) => String -> Consumer m x ()

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

consumeInto :: forall m x. (Monad m, Monoid x) => Consumer m x x

Collects the entire input source into the return value.

Generic transducers

parse :: forall m x y. (Monad m, Monoid x) => Parser m x y

Transducer parse prepares input content for subsequent parsing.

unparse :: forall m x b. (Monad m, Monoid x) => Transducer m [Markup b x] x

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

parseSubstring :: forall m x. (Monad m, Eq x, LeftReductiveMonoid x, FactorialMonoid x) => x -> Parser 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.

data OccurenceTag

Used by parseSubstring to distinguish between overlapping substrings.

Instances

Enum OccurenceTag

Eq OccurenceTag

Show OccurenceTag

count :: forall m x. (Monad m, FactorialMonoid x) => Transducer m x [Integer]

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

toString :: forall m x. (Monad m, Show x) => Transducer m [x] [String]

Converts each input value x to show x.

List stream transducers

The following laws hold:

• group >>> concatenate == id
• concatenate == concatSeparate []

group :: forall m x. (Monad m, Monoid x) => Transducer m x [x]

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

concatenate :: forall m x. (Monad m, Monoid x) => Transducer m [x] x

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

concatSeparate :: forall m x. (Monad m, MonoidNull x) => x -> Transducer m [x] x

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

Generic splitters

everything :: forall m x. Monad m => Splitter m x

Splitter everything feeds its entire input into its true sink.

nothing :: forall m x. (Monad m, Monoid x) => Splitter m x

Splitter nothing feeds its entire input into its false sink.

marked :: forall m x y. (Monad m, Eq y) => Splitter m [Markup y x]

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

markedContent :: forall m x y. (Monad m, Eq y) => Splitter m [Markup y x]

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

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

Splitter 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 :: forall m x y. (Monad m, Eq y) => (y -> Bool) -> Splitter m [Markup y x]

Splitter 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 :: forall m x. (Monad m, FactorialMonoid x) => Splitter m x

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

substring :: forall m x. (Monad m, Eq x, LeftReductiveMonoid x, FactorialMonoid x) => x -> Splitter m x

Splitter 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

lowercase :: forall m. Monad m => Transducer m String String

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

uppercase :: forall m. Monad m => Transducer m String String

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

whitespace :: forall m. Monad m => Splitter m String

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

letters :: forall m. Monad m => Splitter m String

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

digits :: forall m. Monad m => Splitter m String

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

line :: forall m. Monad m => Splitter 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".

nonEmptyLine :: forall m. Monad m => Splitter m String

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

Consumer, producer, and transducer combinators

consumeBy :: forall m x y r. Monad m => Consumer m x r -> Transducer m x y

Converts a Consumer into a Transducer with no output.

prepend :: forall m x r. Monad m => Producer m x r -> Transducer m x x

Combinator prepend converts the given producer to a Transducer that passes all its input through unmodified, except for prepending the output of the argument producer to it. The following law holds: prepend prefix = join (substitute prefix) id

append :: forall m x r. Monad m => Producer m x r -> Transducer m x x

Combinator append converts the given producer to a Transducer that passes all its input through unmodified, finally appending the output of the argument producer to it. The following law holds: append suffix = join id (substitute suffix)

substitute :: forall m x y r. (Monad m, Monoid x) => Producer m y r -> Transducer 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.

class PipeableComponentPair m w c1 c2 c3 | c1 c2 -> c3, c1 c3 -> c2, c2 c3 -> c2, c1 -> m w, c2 -> m w, c3 -> m

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.

Instances

(Monad m, Monoid x) => PipeableComponentPair m x (Producer m x r) (Consumer m x ()) (Performer m r)

(Monad m, Monoid x) => PipeableComponentPair m x (Producer m x ()) (Consumer m x r) (Performer m r)

(Monad m, Monoid x) => PipeableComponentPair m x (Producer m x ()) (Consumer m x ()) (Performer m ())

(Monad m, Monoid x, Monoid y, Monoid z) => PipeableComponentPair m y (Transducer m x y) (Transducer m y z) (Transducer m x z)

(Monad m, Monoid x, Monoid y) => PipeableComponentPair m x (Producer m x r) (Transducer m x y) (Producer m y r)

(Monad m, Monoid x, Monoid y) => PipeableComponentPair m y (Transducer m x y) (Consumer m y r) (Consumer m x r)

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

class (Monad m, CompatibleSignature c1 t1 m x y, CompatibleSignature c2 t2 m x y, CompatibleSignature c3 t3 m x y) => JoinableComponentPair t1 t2 t3 m x y c1 c2 c3 | c1 c2 -> c3, c1 -> t1 m, c2 -> t2 m, c3 -> t3 m x y, t1 m x y -> c1, t2 m x y -> c2, t3 m x y -> c3 where

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, and
• 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.

Methods

sequence :: c1 -> c2 -> c3

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

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

The join combinator may apply the components in any order.

Splitter combinators

sNot :: forall m x. (Monad m, Monoid x) => Splitter m x -> Splitter 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

Combinators >& and >| are only pseudo-logic. While the laws of double negation and De Morgan's laws hold, sAnd and sOr are in general not commutative, associative, nor idempotent. In the special case when all argument splitters are stateless, such as those produced by statelessSplitter, these combinators do satisfy all laws of Boolean algebra.

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

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

Zipping logic combinators

The && and || combinators run the argument splitters in parallel and combine their logical outputs using the corresponding logical operation on each output pair, in a manner similar to zipWith. They fully satisfy the laws of Boolean algebra.

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

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

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

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

Flow-control combinators

The following combinators resemble the common flow-control programming language constructs. Combinators wherever, unless, and select are just the special cases of the combinator ifs.

• transducer `wherever` splitter = ifs splitter transducer id
• transducer `unless` splitter = ifs splitter id transducer
• select splitter = ifs splitter id suppress

ifs :: (MonadParallel m, Monoid x, Branching c m x ()) => Splitter m x -> c -> c -> c

wherever :: (MonadParallel m, Monoid x) => Transducer m x x -> Splitter m x -> Transducer m x x

unless :: (MonadParallel m, Monoid x) => Transducer m x x -> Splitter m x -> Transducer m x x

select :: forall m x. (Monad m, Monoid x) => Splitter m x -> Transducer m x x

Recursive

while :: (MonadParallel m, MonoidNull x) => Transducer m x x -> Splitter m x -> Transducer 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) => Splitter m x -> Splitter m x -> Splitter 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

All combinators in this section use their Splitter argument to determine the structure of the input. Every contiguous portion of the input that gets passed to one or the other sink of the splitter is treated as one section in the logical structure of the input stream. What is done with the section depends on the combinator, but the sections, and therefore the logical structure of the input stream, are determined by the argument splitter alone.

foreach :: (MonadParallel m, MonoidNull x, Branching c m x ()) => Splitter m x -> c -> c -> 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) => Splitter m x -> Splitter m y -> Splitter 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) => Splitter m x -> Splitter m y -> Splitter 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) => Splitter m x -> Splitter m x -> Splitter m x

Combinator followedBy treats its argument Splitters as patterns components and returns a Splitter 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 :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Splitter 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 :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Splitter 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 :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Splitter 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 :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Splitter 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 :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Splitter 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 :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Splitter 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 :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Splitter 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 :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Splitter m x

Splitter 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 :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Splitter m x

Splitter 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) => Splitter m x -> Splitter m x -> Splitter 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

splitterToMarker :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Transducer m x [(x, Bool)]

parseRegions :: forall m x. (Monad m, MonoidNull x) => Splitter m x -> Parser m x ()

Converts a splitter into a parser.

Parsing XML

xmlTokens :: Monad m => Splitter m Text

XML markup splitter wrapping parseXMLTokens.

parseXMLTokens :: Monad m => Transducer 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.

expandXMLEntity :: String -> String

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

data XMLToken

Constructors

StartTag

EndTag

EmptyTag

ElementName

AttributeName

AttributeValue

EntityReference

EntityName

ProcessingInstruction

ProcessingInstructionText

Comment

CommentText

StartMarkedSectionCDATA

EndMarkedSection

DoctypeDeclaration

ErrorToken String

Instances

Eq XMLToken

Show XMLToken

XML splitters

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

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

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

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

xmlElementName :: Monad m => Splitter 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.

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

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

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

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

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

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

xmlElementHavingTagWith :: forall m b. Monad m => Splitter m [Markup XMLToken Text] -> Splitter 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.