[sokoloff]

Even with lookahead, it seems like there are ambiguous cases. I think the "hacky and fragile" level is so high, that it rises to a level of "practically required" to avoid ambiguity. (In the sense of "if John McCarthy had proposed it the other way in an early draft, it would have been peer reviewed out before the first implementation.")

In a sequence of expressions, how would I [or the computer] know how to evaluate the following

  g (a b) h (c d)

If g (a b) returns a function f and h (c d) returns a value v, should the result of that evaluation be v or f(v)?

Does our intuition change if I write it as:

  g (a b) 
  h (c d)

If the default is for the result to be v, and I do want it to be f(v), it's not obvious to me how to re-write it, whereas it's obvious if the first element in a list is a function call:

  (g (a b))  ; ==> f
  (h (c d))  ; ==> v

vs

  ((g (a b)) (h (c d)))   ; ==> (f (v))