ahem/lib/ahem/ast/function_definition.rb

class AST::FunctionDefinition
  attr_reader :name, :parameters, :body

  def initialize(name, parameters, body)
    @name = name
    @parameters = parameters
    @body = body
  end

  def ==(other)
    other.is_a?(AST::FunctionDefinition) && other.name == @name &&
      other.parameters == @parameters &&
      other.body == @body
  end

  def execute(env)
    env.set(@name.name, self)
  end
end