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enumerable_lz

'enumerable_lz' provides filter and transformation methods in Enumerable module. Also it provides lazy equivalents of some methods in Enumerable.

Fundamental Usage

When require 'enumerable_lz', these lazy methods are provided:

  • Enumerable#filter
  • Enumerable#transform

And some method-chains are provided:

  • Enumerable#filter.with_index
  • Enumerable#filter.with_initializer
  • Enumerable#transform.with_index

For example (in Ruby 1.9.x or greater):

require 'enumerable_lz'
require 'prime'

(1..Float::INFINITY).transform{|n|n**2+1}.filter{|m|m.prime?}.take(100)
# => [2, 5, ... , 682277, 739601] for a few msec.

Prime.filter.with_index{|q,i|i.odd?}.take(10)
# => [3, 7, 13, 19, 29, 37, 43, 53, 61, 71]

Prime.transform.with_index{|q,i|[q,i]}.take(10)
# => [[2, 0], [3, 1], [5, 2], [7, 3], [11, 4], [13, 5], [17, 6], [19, 7], [23, 8], [29, 9]]

# especially, when calling transform.with_index without a block
Prime.transform.with_index.take(10)
# => [[2, 0], [3, 1], [5, 2], [7, 3], [11, 4], [13, 5], [17, 6], [19, 7], [23, 8], [29, 9]]

Expanded Usage

When require 'enumerable_lz/enumerable_ex', some lazy methods equivalents to original Enumerable method with suffix '_lz' are provided:

  • Enumerable#select_lz
  • Enumerable#find_all_lz
  • Enumerable#reject_lz
  • Enumerable#grep_lz
  • Enumerable#map_lz
  • Enumerable#collect_lz
  • Enumerable#drop_lz
  • Enumerable#drop_while_lz
  • Enumerable#take_lz
  • Enumerable#take_while_lz

For example (in Ruby 1.9.x or greater):

require 'enumerable_lz'
require 'enumerable_lz/enumerable_ex'
require 'prime'

(1..Float::INFINITY).map_lz{|n|n**2+1}.select_lz{|m|m.prime?}.take_lz(100).to_a
# => [2, 5, ... , 682277, 739601] for a few msec.

These expanded methods are inplemented with fundamental filter and transformation methods.

Supported Rubies

  • Ruby 2.1.0 (testing 2.1.0-p0)
  • Ruby 2.0.0 (testing 2.0.0-p247)
  • Ruby 1.9.x (testing 1.9.3-p448)
  • Ruby 1.8.7 (testing 1.8.7-p358)
  • JRuby (testing 1.7.2)
  • MacRuby (testing 0.12)

Installation

gem install enumerable_lz

License

The MIT License
Copyright (c) 2011, 2014 GOTOH Shunsuke (@antimon2)

Please see LICENSE.txt for details.