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Contents
require 'funkr/categories'
# Extends array (as list) capabilities
class Array
include Funkr::Categories
class << self
def unit(e); self.new([e]); end
alias pure unit
def mzero; self.new(); end
end
### Categories
# Array is already a functor with its correct map implementation
# Array can be made an applicative functor, for example :
#
# f = Array.curry_lift_proc{|x,y| x + y}
# f.apply([0,4]).apply([5,7]) => [5, 7, 9, 11]
# f.apply([0,4]).apply([]) => []
include Applicative
extend Applicative::ClassMethods
def apply(to)
map do |f|
to.map{ |t| f.call(t)}
end.flatten(1)
end
# Array is Alternative whith empty? being zero
include Alternative
# [].or_else{[5]} => [5]
def or_else(&block)
if empty? then yield
else self end
end
# Array is a monoid with mplus = (+) and mzero = []
include Monoid
extend Monoid::ClassMethods
# [5].mplus([6]) => [5,6]
def mplus(m_y)
self + m_y
end
include Monad
extend Monad::ClassMethods
# Array is also a monad
#
# [1,2].bind{|x| [3,4].bind{|y| x + y}} # => [4,5,5,6]
def bind(&block)
self.map(&block).flatten(1)
end
def self.box(value)
if value.nil? then self.mzero
else self.unit(value) end
end
def unbox()
if self.empty? then nil
else self.first end
end
end
Version data entries
5 entries across 5 versions & 1 rubygems