# Copyright (c) 2011 Edward Langley
 # All rights reserved.
 # 
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 # 
 # Redistributions of source code must retain the above copyright notice,
 # this list of conditions and the following disclaimer.
 # 
 # Redistributions in binary form must reproduce the above copyright
 # notice, this list of conditions and the following disclaimer in the
 # documentation and/or other materials provided with the distribution.
 # 
 # Neither the name of the project's author nor the names of its
 # contributors may be used to endorse or promote products derived from
 # this software without specific prior written permission.
 # 
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 # TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 # PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 # LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 

 
 def f(h):
   def g(n):
      if n <= 1: return 1
      else: return n*h(n-1)
 
 #def e(h):
 #  def
 
 def Y(f):
   def g(h):
     def i(x):
       return f(h(h))(x)
     return i
   return g(g)
 
 
 @Y
 def fib(f):
     def _inner(n):
         if n in range(2): return 1
         else: return f(n-1) + f(n-2)
     return _inner
 
 
 import functools
 
 def bounce(func):
   @functools.wraps(func)
   def _inner(arg):
     result = func(arg)
     return result(fact)
   return _inner
 
 class return_if(object):
     def __init__(self, map):
         self._map = dict(
             (tuple(k) if hasattr(k, '__iter__') else (k,),v) for k,v in map.iteritems()
         )
         self._func = lambda x:x
     def _inner(self, *args):
         if args in self._map: return self._map[args]
         else: return self._func(*args)
     def __call__(self, func):
         self._func = func
         return self._inner
 @bounce
 @return_if({1: lambda _:1})
 def fact(n):
     return lambda x: n*x(n-1)