when attempting to compute square roots using the new `new-if` procedure (which acts as `if` however is not a special form), all three of the arguments to `new-if` must be fully evaluated before the `new-if` can return a value. this is in contrast to the special form `if` which only ever evaluates one of the second and third arguments, conditional on the first argument.

in this case, even if the current guess is good enough (indicating that the second argument of the `new-if` should be returned) the procedure is still required to evaluate the third argument, which contains a recursive call.

as such, using the non-special form `new-if` will never return a value, as it has no way of stopping evaluation once a good enough answer has been found.