Each versus for-each and for-all

Development Foreign Inspiration
5

While rethinking the nature of arity-1 WHILE and shifting the arity-2 WHILE semantics to LOOP, it made me think that maybe this needs reordering.

>> for x each [1 2] [print ["running" x, x + 10]]
running 1
running 2
== 12

This would mean EACH [1 2] would be the generator, and X would be a property of FOR. That gives flexibility in defining FOR for other argument values. Integer could just count up:

>> for x 2 [
      print ["running" x], x + 10
   ]
running 1
running 2
== 12

FOR X EACH and FOR-EACH X are the same number of characters, with the former having nicer visual possibilities. This is especially true when differentiating a block for variable names from the iterated variables:

for-each [a b] [1 2 3 4] [print [a b]]

for [a b] each [1 2 3 4] [print [a b]]

This makes EACH as a generator much clearer:

 >> g: each [1 2]

 >> g
 == 1

 >> g
 == 2

 >> g
 ; null

Under this setup, a FOR which did not use an EACH could reserve BLOCK! for other meanings, such as a dialect for ranges.

for x [1 to 10] [print [x]]
for x [1 thru 10] [print [x]]

But since that puts a lot of "logic" into FOR, we might make EACH the default semantics of a series with FOR and then make this dialect the weird case. Otherwise you're kind of wasting the short word on cases like strings. But it's hard to think of a good short name for that generator dialect:

for x yournamehere [1 to 10] [print [x]]
for x yournamehere [1 thru 10] [print [x]]

Anyway...if FOR was generalized in this way, it could free up REPEAT for something that might make more sense: namely "do the same thing N times". But this could be distinguished from loop by paying attention to the truthiness of the body:

>> n: 0
>> repeat 10 [  ; a WHILE variant, limited by a count.
      print "Repeating"
      n < 3
   ]
Repeating
Repeating
Repeating
Repeating

This combination of "heeds the count, but stops earlier if the body returns false" may seem odd. But this formulation could make repeating a rule N times in PARSE more clear when it's hidden behind a variable.

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