module Referential

# File lib/referential.rb, line 8
def cref(method_name)
  redefine!(singleton_class, method_name, method(method_name).arity)
end

# File lib/referential.rb, line 4
def ref(method_name)
  redefine!(self, method_name, instance_method(method_name).arity)
end

# File lib/referential.rb, line 26
def new_name(method_name)
  "fun_#{method_name}".to_sym
end

# File lib/referential.rb, line 14
def redefine!(context, method_name, arity)
  raise 'Cannot compose methods with splat, keyword or default arguments!' if arity < 0

  context.alias_method new_name(method_name), method_name
  context.undef_method method_name

  context.define_method(
    method_name,
    &reference_block(new_name(method_name), arity)
  )
end

# File lib/referential.rb, line 30
def reference_block(new_name, arity)
  proc do |*args|
    proc { |*args| method(new_name).call(*args) }
      .curry(arity)
      .call(*args)
  end
end