Is it possible to recursively update a function?

My foolish move for this week: I'm going to go way out on a limb and 
guess what the OP wanted was something like this.

i=1, foo = x*exp(-x)

i=2, foo= x^2*exp(-x)
i=3, foo = x^3*exp(-x)
.
.
.


In which case he really should create a vector bar<-rep(na,5) ,
and then inside the loop,

bar[i]<-x^i*foo(x)


Carl



quoted material:
Date: Thu, 04 Mar 2010 11:37:23 -0800 (PST)


I need to update posterior dist function upon the coming results and 
find the posterior mean each time.

> What exactly are you trying to do?  'foo' calls 'foo' calls 'foo' ....
 >  How did you expect it to stop the recursive calls?
 >
 >
 >
 >
 >

> > Here is the test code.
 >
 > > foo<-function(x) exp(-x)
 > > for (i in 1:5)
 > > {
 > > foo<-function(x) foo(x)*x
 > > foo(2)
 > > }