functional/README.md

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

Thanks to `Symbol#to_proc`:

	Sequence.new.to_fun.
		select( &:even?).
		collect {|i| i/3 }.
		select( &:even?).
		collect {|i| [[[[[[i.even?, i.odd?]]], i, [[[[[[i.class]]]]]]]]] }.
		flatten. # It flattens everything! Not like: collect {|i| i.flatten }.
		p

If you know methodphitamine,  combine it:

	require 'methodphitamine'
	
	Sequence.new.to_fun.
		select( &it.even?).
		collect( &it/3).
		select( &it.even?).
		collect {|i| [[[[[[i.even?, i.odd?]]], i, [[[[[[i.class]]]]]]]]] }.
		flatten.
		p

	(0..100000).to_fun.
		collect( &it*3).
		select( &it%5 == 2).
		to_a

Makros
======

	seq = Sequence.new.to_fun
	seq = seq.select &it.even?  if must_be_even
	seq = seq.
		collect( &it/3).
		select( &it.even?).
		collect {|i| [[[[[[i.even?, i.odd?]]], i, [[[[[[i.class]]]]]]]]] }
	seq = seq.flatten  if please_flatten
	if print_it
		seq.p
	else
		seq_to_a
	end

What's with _#map_?
=================

Do you know MapReduce?  In future #map will be used for MapReduce.  Use #collect.