It's a four paragraph blog post answering the question "why?". I'm not sure why you expect him to delve into the how at this stage: he probably doesn't have anything fully formed yet.
Look at us salivating for his big unveil -- we've probably already written more than he did
Looks like the syntax is taking shape at least.
For the first, I think it's a mistake to perpetuate the mistakes of the past. I don't think JS developers have had problems adjusting to the lack of return in arrow functions.
Beginners have no preconceived notions of how a programming language should operate, and return makes the language model more complex.
1 + 1 evaluates to 2, but (in a language that requires return)
def foo = 1 + 1
foo
doesn't for no good reason. This breaks the simple substitution model of evaluation.
These claims could be addressed emperically, but I guess neither of us are going to do the research. :-)
For example, which of these is more clear to people who don't know Lisp? I'd argue the second one because of the early return if guard.
---- THIS ----
(defun sum-helper (items total)
(cond
(items
(sum-helper
(cdr items)
(+ total (car items))))
(t total)))
(defun sum (&rest items)
(sum-helper items 0))
(print (sum 1 2 3 4))
----- OR -----
(defun sum-helper2 (items total)
(if (not items)
(return-from sum-helper2 total))
(sum-helper2
(cdr items)
(+ total (car items))))
(defun sum2 (&rest items)
(sum-helper2 items 0))
(print (sum2 5 6 7 8))(It should be readable but hasn't had a final editing pass.)