なんでRubyで関数合成できねぇンだよ( ;ﾟ皿ﾟ)ﾉｼΣ ﾌｨﾝｷﾞｨｨｰｰｯ!!!

compose.rb

# Rubyで関数合成
#
# irb(main):016:0> f = "foo".method(:==)
# => #<Method: String#==>
# irb(main):017:0> g = lambda{|x| puts "result : #{x}"}
# => #<Proc:0x007fdafa06c0c0@(irb):17 (lambda)>
# irb(main):018:0> (f >> g).call("foo")
# result : true
# => nil
# irb(main):019:0> (f >> :to_s).call("hoge")
# => "false"
module ComposableFunction
  def >>(g)
    lambda{|*args| g.to_proc.call(self.to_proc.call(*args)) }
  end

  def <<(g)
    g.to_proc >> self
  end
end

[Proc, Method, Symbol].each do |klass|
  klass.send(:include, ComposableFunction)
end