# This file is part of NIT ( http://www.nitlanguage.org ). # # Copyright 20042008 Jean Privat <jeanpryen.org # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.orglicensesLICENSE2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. # A simple exemple of refinement where a method is added to the integer class. module fibonacci redef class Int # Calculate the self-th element of the fibonacci sequence. fun fibonacci: Int do if self < 2 then return 1 else return (self-2).fibonacci + (self-1).fibonacci end end end # Print usage and exit. fun usage do print "Usage: fibonnaci <integer" exit 0 end # Main part if args.length != 1 then usage end print args.first.to_i.fibonacci