LETREC (REC)

[Bill Rozas <JINX%OZ.AI.MIT.EDU@XX.LCS.MIT.EDU>]

    The problem is that this particular over restriction really diminishes
    the power of the language; no clever macrology (in the current RRRS)
    is going to allow general higher order functions to generate recursive
    functions.  (By general, I mean higher order functions which don't
    specifically expect to generate recursive functions).

This is not true.  While it becomes more complicated, it is possible
to do it.  I don't remember your precise example but there is a simple
trick which makes it work and satifies the constraint I like.  The
trick is the same as the one used in converting the normal order Y
operator into applicative order.  Questions of efficiency might arise
if there is no procedure integration or the compiler is not
able to deduce what's going on or allowed to use this information.