An naïve implementation of a Closure object in Ruby

closure.rb

class Closure
  attr_reader :formals, :bodies, :env
  def initialize(formals, bodies, env)
    @formals = Array(formals)
    @bodies = Array(bodies)
    @env = env
  end

  def call(*args)
    raise argument_error(args) if args.length != formals.length
    bodies.map {|body| body.call(env.merge(bind(args))) }.last
  end

  def bind(args)
    formals.zip(args).each_with_object({}) do |(key, value), hash|
      hash[key] = value
    end
  end

  def argument_error(args)
    ArgumentError.new("wrong number of arguments (#{args.length} for #{formals.length})")
  end
end

# Examples:

body = lambda {|env| puts "#{env[:level]}: #{env[:format] % env[:args]}" }
logger = Closure.new([:level, :format, :args], body, {})
logger.call(:info, "%s on the bridge of the %s", ["Kirk", "Enterprise"])