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* [[APL+]] finds empty arrays everywhere, even where they would extend beyond the edges of the right argument. | * [[APL+]] finds empty arrays everywhere, even where they would extend beyond the edges of the right argument. | ||
=== Discussion === | === Discussion === | ||
In February, April, and May, [[Dyalog Ltd]] had internall discussions about the correctness of the implemented primitive for empty left arguments.<ref>[[Dyalog Ltd]]. Internal emails. ''more ⍷ follies | In February, April, and May of 2021, [[Dyalog Ltd]] had internall discussions about the correctness of the implemented primitive for empty left arguments.<ref>[[Dyalog Ltd]]. Internal emails. ''more ⍷ follies | ||
'', 15–19 Feb; ''ancient bug in ⍷ with empty left argument'', 7–8 Apr, and 26 May 2021.</ref> | '', 15–19 Feb; ''ancient bug in ⍷ with empty left argument'', 7–8 Apr, and 26 May 2021.</ref> | ||
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In May, Brudzewsky found support for Kromberg's theory, based on that exact usage in a conference proceeding,<ref>[[Adin Falkoff|Falkoff, Adin]]. [A note on pattern matching: Where do you find the match to an empty array?] [[APL79]]. doi:[https://doi.org/10.1145/800136.804470 10.1145/800136.804470].</ref> finding that redefining <source lang=apl inline>≡</source> accordingly as <source lang=apl inline>{(⍺≡⍥⍴⍵)∧(∧/⍺≡¨⍥,⍵)}</source> would make Hui's <source lang=apl inline>ebar</source> model align with the behaviour of the primitive as implemented. Hui promised to write an appendix to his earlier forum post ''at an appropriate time'', but passed away before being able to do so. | In May, Brudzewsky found support for Kromberg's theory, based on that exact usage in a conference proceeding,<ref>[[Adin Falkoff|Falkoff, Adin]]. [A note on pattern matching: Where do you find the match to an empty array?] [[APL79]]. doi:[https://doi.org/10.1145/800136.804470 10.1145/800136.804470].</ref> finding that redefining <source lang=apl inline>≡</source> accordingly as <source lang=apl inline>{(⍺≡⍥⍴⍵)∧(∧/⍺≡¨⍥,⍵)}</source> would make Hui's <source lang=apl inline>ebar</source> model align with the behaviour of the primitive as implemented. Hui promised to write an appendix to his earlier forum post ''at an appropriate time'', but passed away before being able to do so. | ||
It is | It is | ||
== See also == | == See also == | ||
* [[Membership]] | * [[Membership]] | ||