Re: [Bug-apl] A few problems

[Dr . Jürgen Sauermann]

Hi, I am pretty sure that GNU APL behaves according to the ISO standard up to the point where it crashes. The only wrong behaviour that I currently see is that it should catch the bad alloc exception and signal WS full instead of looping forever. I will look into this. Thanks. Every design decision depends on local constraints. Though, why not to use look-ahead and detect that as incorrect assignment to a function? I see it as a more direct and clean approach. Would it be too difficult to implement? With best regards. There are a nu,ber of reasons for not doing this. The first one that comes to my mind is that assignments are only one case of a niladic function causing infinite recursion. Considert ∇A  A+1 HALT: 'HALTED' ∇ ∇B  B×1 HALT: 'HALTED' ∇ ∇C  A+G HALT: 'HALTED' ∇ ... All ot them are legal APL and would make perfectly sense if  each function would contain a check that terminates the recursion. As far as I understand computer science, this directly leads to the halting problem which is known to be not decidable. Attempting to solve a not decidable problem at runtime is nothing that I would dare to try. Best Regards, /// Jürgen Sauermann