Lazing

Lazing provides lazy equivalents for many of the methods in Ruby's standard Enumerable module. The lazy variants all end in 'ing', hence the name.

For example:

>> (1..20).selecting {|x| raise 'boom' if x == 6; x.odd?}.first(3)
 => [1, 3, 5]

Compare the above with the behavior of the non-lazy standard version:

>> (1..20).select {|x| raise 'boom' if x == 6; x.odd?}.first(3)
RuntimeError: boom
  from (irb):4:in `block in irb_binding'
  from (irb):4:in `each'
  from (irb):4:in `select'
  from (irb):4
  from irb:17:in `<main>'

Lazy Methods

Lazing defines the following lazy filter methods:

• finding_all
• rejecting
• selecting

Lazing defines the following lazy transformation methods:

• collecting
• mapping

Supported Rubies

Lazing requires Ruby 1.9. It has been tested with:

• Ruby 1.9.1-p378
• Ruby 1.9.2-p0

Installation

Lazing is distributed as a gem. To install, use the command:

gem install lazing

Obtaining the Latest Version

Lazing is hosted on github at http://github.com/gregspurrier/lazing.

A local clone of the repository can be obtained via:

git clone git://github.com/gregspurrier/lazing.git

Related work

After implementing select_first for a project I was working on, I searched for lazy enumeration support in Ruby. I came across this blog post and it became the inspiration for Lazing.

I later discovered that my implementation of selecting is almost identical to the infinite_select example given in Programming Ruby: The Pragmatic Programmers' Guide by Dave Thomas.

License

Lazing is Copyright (c) 2010 by Greg Spurrier and released under the terms of the MIT License. Please see LICENSE.txt for details.