Re: APL2 Compatibility

[Jay Foad]

I don't see "operand" as a neutral term. It is defined on p24:
"Operators take functions or arrays as /operands/"

Jay.

On Mon, 30 Nov 2020 at 14:20, Dr. Jürgen Sauermann
<mail@jürgen-sauermann.de> wrote:
>
> Hi Jay,
>
> I see, thanks. I was thinking of the table "NAME AND SYMBOL BINDING"
> on page 21 and repeated on page 34. It uses the neutral term "left operand"
> without being specific whether that operand is a value, a function or an 
> operator.
>
> I read the sentence you quote somewhat differently. Not in the sense that
> one operator cannot be the left or operand of another operator but rather 
> that the
> binding rules concerning operands of operators shall not apply if an operand 
> is
> itself an operator. The example that follows wisely excluded the case where
> an operator like / could also be evaluated as a function.
>
> I believe the sentence is equivalent to saying, in parser terms, that OP OP 
> shall
> be shifted rather than being reduced. That will unfortunately create more 
> derived
> functions, but these cases are so rare that that will not matter. I will 
> therefore
> see what happens if I remove all parser reductions with adjacent operators
> from the phrase table of GNU APL and see if that causes new problems
> (I suppose at least some automatic testcases will fail).
>
> Best Regards,
> Jürgen
>
>
> On 11/30/20 1:25 PM, Jay Foad wrote:
>
> My
>
> 1 / / 1 1 ⍴ 1
>
> example was only meant to demonstrate that in APL2 an operator can have
> another operator (in this case itself) as left argument. And in that case 
> binding
> the leftmost 1 to the left / operator would be, at least IMHO and referring 
> only
> to the language reference manual, as valid as binding the left / operator to 
> the
> right / operator.
>
> I don't think so. See the discussion of "Name and Symbol Binding"
> starting on p33, and in particular on p35:
>
> "There is no binding between operators. In the expression ,¨/ catenate binds 
> as
> left operand to the each operator, and then the derived function ,¨
> binds as left
> operand to the slash operator."
>
> Jay.
>
>