Re: Recursive anonymous functions?

[Gabor Grothendieck <ggrothendieck@...>]

Rici Lake <lua <at> ricilake.net> writes:

: 
: On 22-Jul-04, at 9:31 PM, Gabor Grothendieck wrote:
: >
: > For example, we can invoke the anonymous factorial function
: > evaluating it for the argument 3 like this:
: >
: >    Recall = function(...)
: >      return debug.getinfo(2,"f").func(unpack(arg))
: >    end
: 
: The use of the debug library is not advisable, unless you are actually 
: debugging. Furthermore, this will not work on the tail-recursive 
: implementation of factorial:
: 
: print ((function(x, acc)
:            if x <= 1 then return acc
:                      else return Recall(x - 1, x * acc)
:            end
:          end) (3, 1))
: 
: stdin:1: attempt to call field `func' (a nil value)

That's too bad; however, one can still do it in a consistent,
but uglier, way for both examples by using 

   debug.getinfo(1,"f").func

inline like this:

   print ((function(x)
           if x == 0 then return 1
                     else return x * debug.getinfo(1,"f").func(x - 1)
           end
         end) (3, 1))
  
   print ((function(x, acc)
           if x <= 1 then return acc
                     else return debug.getinfo(1,"f").func(x - 1, x * acc)
           end
         end) (3, 1))