Ruby Procs and Lamdas

gistfile1.txt

l = -> { return :hi_from_lamda }
pr = proc { return :hi_from_proc }

def foo
  yield if block_given?
  return :hi_from_method
end

# foo :hi_from_method
# foo(&l) # :hi_from_method
# foo { :hi_from_block } # :hi_from_method

# foo(&pr) # :hi_from_proc
# foo { return :hi_from_block } :hi_from_block

def bar(&block)
  block.call
  return :hi_from_method
end
# bar(&l) :hi_from_method
# bar { :hi_from_block } :hi_from_method

# bar(&pr) :hi_from_proc
# foo { return :hi_from_block } :hi_from_block

def baz(block)
  block.call
  return :hi_from_method
end

class Baz
  def call
    return :hi_from_baz
  end
end
# baz(l) :hi_from_method
# baz(pr) :hi_from_proc

# baz(Baz.new) :hi_from_method

# Lamdas have a special syntax because their idea of return is like any other object
# Lamdas are anonymous, 1 method objects
# Everything is an object
# Lamdas have almost no surface area

# RUBY_VERSION 2.4.1
# -> {}.methods.count 76
# Object.methods.count 115
# Hash.methods.count 117


# Think about Object oriented code that doesn't use polymorphism
# Service Objects
# Lamdas are a great API for Service Objects
ll = -> {}
ll.call
ll.() # great for CreateEnterpriseUser.()
ll[] # Most hax - implies some level of predictable access

# Partial Evaluation with #curry
# allows you to get back that initializer you miss
require 'open-uri'
adder = -> x, y { open(x).read.chars.count + y }
c = adder.curry['https://rubygems.org']
# c[2] 11170
# c[4] 11172

# Somewhat congruent to the below

class Faz
  require 'open-uri'
  def initialize(x)
    @count = open(x).read.chars.count
  end

  def call(x)
    @count + x
  end
end