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.

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
• 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.

Components

Sources

A source emits items. See Ryu::Source.

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 exist.

What does this module do?

Nothing. It's just a top-level loader for pulling in all the other components.

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

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
• 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

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

LICENSE

Copyright Tom Molesworth 2011-2019. Licensed under the same terms as Perl itself.