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. > >
