I have a copy of the first edition APL2 LRM from 1982. It specifies two special System Labels: ⎕FL and ⎕ID. ⎕FL: was used to label the fill function so that the programmer could specify precisely what the fill function should be within the scope of the function definition. Similarly, ⎕ID was used to denote the identity operation (for defined operators with empty arguments). This facility was removed from later versions of the manual. There must have been some issue with this approach. Any ideas?
On Mon, May 4, 2020 at 1:08 PM Kacper Gutowski <mwgam...@gmail.com> wrote: > On Mon, May 04, 2020 at 10:43:25AM +0100, Jay Foad wrote: > >Interesting. Dyalog APL is different: if you apply f¨ to empty > >argument(s), it applies f once to the prototypical items of the > >argument(s) to determine the prototypical item of the result. > > Yes, I liked the idea until I realized this includes side effects. > > >I'm not sure what NARS2000 does. > > DOMAIN ERROR > > > -k > >
