Ruby functions vs methods

Question

In the Ruby Programming Language, Chapter 6 (second paragraph) they state:

Many languages distinguish between functions, which have no associated

Answer 1

Procs and lambdas are both objects unto themselves, with a call method that actually invokes the block associated with the proc (or lambda). However, Ruby provides some syntactic sugar to invoke them without the explicit call to call.

Answer 2

lambdas in Ruby are objects of class Proc. Proc objects don't belong to any object. They are called without binding them to an object.

Methods are objects of either class Method or UnboundMethod, depending on whether they're bound or unbound. See the explanation here. Unbound methods can't be called until they're bound to an object.

lambda{|x| x}.class      # => Proc
lambda{|x| x}.call(123)  # => 123

class Foo
  def bar(baz)
    baz
  end
end

puts Foo.new.method(:bar).class     # => Method
puts Foo.new.method(:bar).call(123) # => 123

puts Foo.instance_method(:bar).class     # => UnboundMethod
puts Foo.instance_method(:bar).call(123) # => throws an exception

You can bind an UnboundMethod to an object and then call it. But you can't bind a Proc to an object at all. Proc objects can however capture local variables in the surrounding scope, becoming closures.

Answer 3

I think the distinction is between methods and first order function ie. functions that can be passed around as values.