FWIW comparing a number with a literal for equality is not an error but
always not equal
0 = 'a'
0
On Sun, Jun 21, 2020, 7:53 AM bill lam <bbill....@gmail.com> wrote:
> IIRC if. y do.
> is false only if the leading atom of y is 0, otherwise it is true. it
> should be already documented in J dictionary help file.
>
>
> On Sun, Jun 21, 2020, 7:25 AM Paul Jackson <plj...@gmail.com> wrote:
>
>> I've grown accustomed to following some verbs with '' because there's no
>> way to write a niladic verb in J. Unfortunately I have a verb that uses
>> its
>> argument to decide whether to update or not. That led me to learn the hard
>> way that '' is true.
>>
>> try=: 3 : 0
>>
>> if. y do.
>>
>> 'yes'
>>
>> else.
>>
>> 'no'
>>
>> end.
>>
>> )
>>
>> try ''
>>
>> yes
>>
>> I thought I could force a domain error, but no.
>>
>> try {.''
>>
>> yes
>>
>> I thought maybe J was doing {. and that space is non zero, but {.a. is
>> also
>> true, as was everything else I could think of. This may not constitute a
>> bug, but it is unexpected behavior.
>> ----------------------------------------------------------------------
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>>
>
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