Sorry for not trying this in j806, I should install it on my Mac.
Will update.

As for control structures treating _. as false, I was mistaken.
I was actually comparing a float with _., and that returned 0.
Nevertheless, I think control structures should signal _. instead of silently 
accepting it, and perhaps even comparison operators? Either that or have 
comparisons return _. as well. That would probably be more consistent.

Louis

> On 29 Dec 2017, at 22:41, bill lam <[email protected]> wrote:
> 
> This is what I got from J806
>   foo
> 3 : 0
> if. _ - _ do.
> echo 1
> else.
> echo 0
> end.
> EMPTY
> )
>   foo''
> |NaN error: foo
> |   _    -_
>   bar
> 3 : 0
> if. _. do.
> echo 1
> else.
> echo 0
> end.
> EMPTY
> )
>   bar''
> 1
> 
> foo is reasonable.
> bar is also reasonable to me, because _. is not equal 0 so that
> the condition is true.
> 
> What is your code that treating _. as false?
> 
> Also on my J806 linux64
>   2 7 p.1e308j_
> _j_
> 
> 
> Пт, 29 дек 2017, Louis de Forcrand написал(а):
>> What about control structures treating _. as false?
>> I personally would make that an error, and I would also say that code that 
>> makes use of this should be considered bad style.
>> 
>> Louis
>> 
>>> On 29 Dec 2017, at 18:29, Henry Rich <[email protected]> wrote:
>>> 
>>> Surely not intended.  Put it on the bug list.
>>> 
>>> Henry Rich
>>> 
>>> On 12/29/2017 6:06 PM, Louis de Forcrand wrote:
>>>> On the Indeterminate vocabulary page of the dictionary it is written
>>>> 
>>>> The only ways to create _. are as follows:
>>>>    direct entry of _.
>>>>    ".
>>>>    3!:n
>>>>    DLL call (database, LAPACK, etc.)
>>>> 
>>>> and
>>>> 
>>>> Primitives on arguments not containing _. signal NaN error instead of 
>>>> producing _. .
>>>> 
>>>> yet (in j64-805 on macOS 10.10.5)
>>>> 
>>>>   2 7 p.1e308j_
>>>> _.j_
>>>> 
>>>> This is very dangerous, as comparison with _. seems to yield _. and it 
>>>> also seems that control structures treat _. as false instead of signalling 
>>>> an error (which is in my opinion a very bad idea).
>>>> Are both these behaviours intended?
>>>> 
>>>> Thanks,
>>>> Louis
>>>> 
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>>> 
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