NAME

Ryu - asynchronous stream building blocks

SYNOPSIS

 #!/usr/bin/env perl
 use strict;
 use warnings;
 use Ryu qw($ryu);
 my ($lines) =
        $ryu->from(\*STDIN)
                ->by_line
                ->filter(qr/\h/)
                ->count
                ->get;
 print "Had $lines line(s) containing whitespace\n";

DESCRIPTION

Provides data flow processing for asynchronous coding purposes. It's a bit like ReactiveX in concept. Where possible, it tries to provide a similar API. It is not a directly-compatible implementation, however.

For more information, start with Ryu::Source. That's where most of the useful parts are.

Why would I be using this?

Eventually some documentation pages might appear, but at the moment they're unlikely to exist.

• Network protocol implementations - if you're bored of stringing together substr, pack, unpack and vec, try Ryu::Manual::Protocol or Ryu::Buffer.

• Extract, Transform, Load workflows (ETL) - need to pull data from somewhere, mangle it into shape, push it to a database? that'd be Ryu::Manual::ETL

• Reactive event handling - Ryu::Manual::Reactive

As an expert software developer with a keen eye for useful code, you may already be bored of this documentation and on the verge of reaching for alternatives. The "SEE ALSO" section may speed you on your way.

Compatibility

Since RxPerl follows the ReactiveX conventions quite closely, we'd expect to have the ability to connect RxPerl observables to a Ryu::Source, and provide an adapter from a Ryu::Source to act as an RxPerl-style observable. This is not yet implemented, but may be added in a future version.

Most of the other modules in "SEE ALSO" are either not used widely enough or not a good semantic fit for a compatibility layer - but if you're interested in this, please ask about it or provide patches!

Components

Sources

A source emits items. See Ryu::Source. If in doubt, this is likely to be the class that you wanted.

Items can be any scalar value - some examples:

• a single byte

• a character

• a byte string

• a character string

• an object instance

• an arrayref or hashref

Sinks

A sink receives items. It's the counterpart to a source. See Ryu::Sink.

Streams

A stream is a thing with a source. See Ryu::Stream, which is likely to be something that does not yet have much documentation - in practice, the Ryu::Source implementation covers most use-cases.

So what does this module do?

Nothing. It's just a top-level loader for pulling in all the other components. You wanted Ryu::Source instead, or possibly Ryu::Buffer.

Some notes that might not relate to anything

With a single parameter, "from" and "to" will use the given instance as a Ryu::Source or Ryu::Sink respectively.

Multiple parameters are a shortcut for instantiating the given source or sink:

 my $stream = Ryu::Stream->from(
  file => 'somefile.bin'
 );

is equivalent to

 my $stream = Ryu::Stream->from(
  Ryu::Source->new(
   file => 'somefile.bin'
  )
 );

Why the name?

• $ryu lines up with typical 4-character indentation settings.

• there's Rx for other languages, and this is based on the same ideas

• 流 was too hard for me to type

METHODS

Note that you're more likely to find useful methods in the following classes:

• Ryu::Source

• Ryu::Sink

• Ryu::Observable

new

Instantiates a Ryu object, allowing "from", "just" and other methods.

from

Helper method which returns a Ryu::Source from a list of items.

just

Helper method which returns a single-item Ryu::Source.

SEE ALSO

Other modules

Some perl modules of relevance:

• Future - fundamental building block for one-shot tasks

• Future::Queue - a FIFO queue for Future tasks

• Future::Buffer - provides equivalent functionality to Ryu::Buffer

• POE::Filter - venerable and battle-tested, but slightly short on features due to the focus on protocols

• Data::Transform - standalone version of POE::Filter

• List::Gen - list mangling features

• HOP::Stream - based on the Higher Order Perl book

• Flow - quite similar in concept to this module, maybe a bit short on documentation, doesn't provide integration with other sources such as files or IO::Async::Stream

• Flux - more like the java8 streams API, sync-based

• Message::Passing - on initial glance seemed more of a commandline tool, sadly based on AnyEvent

• Rx.pl - a Perl version of the http://reactivex.io Reactive API

• Perlude - combines features of the shell / UNIX streams and Haskell, pipeline syntax is "backwards" (same as grep/map chains in Perl)

• IO::Pipeline

• DS

• Evo

• Async::Stream - early release, but seems to be very similar in concept to Ryu::Source

• Data::Monad

• RxPerl - previously known as Mojo::Rx, targets close compatibility with rxjs

Other references

There are various documents, specifications and discussions relating to the concepts we use. Here's a few:

• http://www.reactivemanifesto.org/

• Java 8 streams API

• C++ range-v3

AUTHOR

Tom Molesworth <TEAM@cpan.org> with contributions from:

• Mohammad S Anwar

• Michael Mueller

• Zak Elep

• Mohanad Zarzour

• Nael Alolwani

• Amin Marashi

LICENSE

Copyright Tom Molesworth 2011-2021. Licensed under the same terms as Perl itself.

cpanm Ryu

perl -MCPAN -e shell
install Ryu