エピソード:Pythonプログラマーの進化史

#     
def factorial(x):
    if x == 0:
        return 1
    else:
        return x * factorial(x - 1)
print factorial(6)
 
#    Pascal       
def factorial(x):
    result = 1
    i = 2
    while i <= x:
        result = result * i
        i = i + 1
    return result
print factorial(6)
 
#    C       
def fact(x): #{
    result = i = 1;
    while (i <= x): #{
        result *= i;
        i += 1;
    #}
    return result;
#}
print(fact(6))
 
#    SICP       
@tailcall
def fact(x, acc=1):
    if (x > 1): return (fact((x - 1), (acc * x)))
    else: return acc
print(fact(6))
 
#    Python       
def Factorial(x):
    res = 1
    for i in xrange(2, x + 1):
        res *= i
    return res
print Factorial(6)
 
#   Python   
def fact(x):
    return x > 1 and x * fact(x - 1) or 1
print fact(6)
 
#    Python   
f = lambda x: x and x * f(x - 1) or 1
print f(6)
 
#   Python   
import operator as op
import functional as f
fact = lambda x: f.foldl(op.mul, 1, xrange(2, x + 1))
print fact(6)
 
#Python   
import sys
@tailcall
def fact(x, acc=1):
    if x: return fact(x.__sub__(1), acc.__mul__(x))
    return acc
sys.stdout.write(str(fact(6)) + '
')
 
#      
import c_math
fact = c_math.fact
print fact(6)
 
#         （  ：      ，“  ”   ，  “maths”，  “math"。）
import c_maths
fact = c_maths.fact
print fact(6)
 
#     
def factorial(x):
    #-------------------------------------------------
    #---        Math Vault      ---
    #---      （C）  ·    1999 ---
    #-------------------------------------------------
    result = str(1)
    i = 1 #    
    while i <= x:
        #result = result * i #It's faster to use *=
        #result = str(result * result + i)
           #result = int(result *= i) #??????
        result str(int(result) * i)
        #result = int(str(result) * i)
        i = i + 1
    return result
print factorial(6)
 
#Unix    
import os
def fact(x):
    os.system('factorial ' + str(x))
fact(6)
 
#Windows    
NULL = None
def CalculateAndPrintFactorialEx(dwNumber,
                                 hOutputDevice,
                                 lpLparam,
                                 lpWparam,
                                 lpsscSecurity,
                                 *dwReserved):
    if lpsscSecurity != NULL:
        return NULL #Not implemented
    dwResult = dwCounter = 1
    while dwCounter <= dwNumber:
        dwResult *= dwCounter
        dwCounter += 1
    hOutputDevice.write(str(dwResult))
    hOutputDevice.write('
')
    return 1
import sys
CalculateAndPrintFactorialEx(6, sys.stdout, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL)
 
#     
def new(cls, *args, **kwargs):
    return cls(*args, **kwargs)
 
class Number(object):
    pass
 
class IntegralNumber(int, Number):
    def toInt(self):
        return new (int, self)
 
class InternalBase(object):
    def __init__(self, base):
        self.base = base.toInt()
 
    def getBase(self):
        return new (IntegralNumber, self.base)
 
class MathematicsSystem(object):
    def __init__(self, ibase):
        Abstract
 
    @classmethod
    def getInstance(cls, ibase):
        try:
            cls.__instance
        except AttributeError:
            cls.__instance = new (cls, ibase)
        return cls.__instance
 
class StandardMathematicsSystem(MathematicsSystem):
    def __init__(self, ibase):
        if ibase.getBase() != new (IntegralNumber, 2):
            raise NotImplementedError
        self.base = ibase.getBase()
 
    def calculateFactorial(self, target):
        result = new (IntegralNumber, 1)
        i = new (IntegralNumber, 2)
        while i <= target:
            result = result * i
            i = i + new (IntegralNumber, 1)
        return result
 
print StandardMathematicsSystem.getInstance(new (InternalBase, new (IntegralNumber, 2))).calculateFactorial(new (IntegralNumber, 6))

次のコードはkohashiが与えたもので、彼は郵便局で見たと言った.

#VBA    
def factorial(x):
    if x == 0:
        return 1
    if x == 1:
        return x
    if x == 2:
        return x * (x-1)
    if x == 3:
        return x * (x-1) * (x-2)
    if x == 4:
        return x * (x-1) * (x-2) * (x-3)
    if x == 5:
        return x * (x-1) * (x-2) * (x-3) * (x-4)
    if x == 6:
        return x * (x-1) * (x-2) * (x-3) * (x-4) * (x-5)
print factorial(6)