This repository has been archived on 2021-12-03. You can view files and clone it, but cannot push or open issues or pull requests.
functional/README.md
2010-06-23 17:01:43 +02:00

55 lines
1.2 KiB
Markdown

Install
=======
gem install functional
Usage
=====
require 'functional'
# To demonstrate Functional, we create a Class with a infinite loop:
class Sequence
include Enumerable
def initialize first = 0, step = 1
@i, @step = first, step
end
def each
# Our infinite loop:
loop do
yield @i
@i += @step
end
end
end
Functional.new( Sequence.new).
select {|i| i.even? }.
collect {|i| i/3 }.
select {|i| i.even?}.
collect {|i| [[[[[[i.even?, i.odd?]]], i, [[[[[[i.class]]]]]]]]] }.
flatten. # It flattens everything! Not like: collect {|i| i.flatten }.
p
# Without Functional... Bye bye.
Sequence.new.
select {|i| i.even? }.
collect {|i| i/3 }.
select {|i| i.even?}.
collect {|i| [[[[[[i.even?, i.odd?]]], i, [[[[[[i.class]]]]]]]]] }.
flatten. # It flattens everything! Not like: collect {|i| i.flatten }.
p
It will never realize, that #p doesn't exists, because the first select runs endless.
Functional#p prints everything to stdout.
(0..100000).to_fun.
collect {|i| i*3 }.
select {|i| i%5 == 2 }.
to_a
What's with _#map_?
=================
Do you know MapReduce? In future #map will be used for MapReduce. Use #collect.