> From: Don Watson
>
> Thanks Ric, that helps.
>
> You are right. I haven't addressed the issue of the (DDD) fork,
> where
> the presence of a left argument establishes that the outer two verbs
> are
> dyadic. In S this would be: (([)*)%([)- . I agree that this
> contains
> extra parentheses. However, it does follow the right to left rule.The
> expression (([)*) is evaluated before the % because of its parentheses.
> In
> S, a dyadic verb is always identified by a noun or a parentheses on its
> immediate left - as is true in non-tacit J programming. This is why an
> extra
> tacit form is not needed.
>
> 7 (* % -) 3 2 does not follow the right to left rule because the *
> is
> not enclosed in parentheses, but is used before the % to its right.
So parentheses are allowed to change the order of execution but still "follow
the left to right rule", but other exceptions aren't?
Are you seriously proposing that students and teachers are more likely to
identify with:
(([)*)%([)-
than the following explicit J expression?
(x*y) % (x-y)
I'd leave the tacit (* % -) for later although I'd still consider it preferable
to the first expression.
Maybe the quest to simplify things by strictly following the right to left rule
(except for parentheses) is getting in the road of your stated objective of
creating a notation that is more useful for teaching maths?
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