Re: Reassignment of a nested array element

[Mr. Sunday]

Thank you for your reply, Hans-Peter.  Sorry for the delay; it took some time 
to dig out my old interpreters.  APL2, APL+Win, and Dyalog come up with the 
answer I expect.  I do not see why reassignment would retain the structure of 
the prior contents.  Is your point of view based upon selective assignment?  
Inserting a comma in the left hand side gives the result you expect: 
(,3⊃var)←⊂⊃'Susan' 'Mary' 'Annalisa'.

IBM APL2 2.0 Service Level 14
 var←0 0 0 ⋄ (1⊃var)←5 4 ⋄ (2⊃var)←3 4⍴⍳12 ⋄ (3⊃var)←⊃'Sue' 'Maria' 'Annalisa' 
⋄ var ⋄ (3⊃var)←⊂⊃'Susan' 'Mary' 'Annalisa' ⋄ var
 5 4   1  2  3  4   Sue      
       5  6  7  8   Maria    
       9 10 11 12   Annalisa 
 5 4   1  2  3  4    Susan     
       5  6  7  8    Mary      
       9 10 11 12    Annalisa  

Dyalog 18.2.45505
  ⎕ml←3 ⋄ ⎕io←1 ⋄ var←0 0 0 ⋄ (1⊃var)←5 4 ⋄ (2⊃var)←3 4⍴⍳12 ⋄ (3⊃var)←⊃'Sue' 
'Maria' 'Annalisa' ⋄ var ⋄ (3⊃var)←⊂⊃'Susan' 'Mary' 'Annalisa' ⋄ var
 5 4  1  2  3  4  Sue      
      5  6  7  8  Maria    
      9 10 11 12  Annalisa 
 5 4  1  2  3  4   Susan     
      5  6  7  8   Mary      
      9 10 11 12   Annalisa  
 
APL+Win 4.0               
 var←0 0 0 ⋄ (1⊃var)←5 4 ⋄ (2⊃var)←3 4⍴⍳12 ⋄ (3⊃var)←⊃'Sue' 'Maria' 'Annalisa' 
⋄ var ⋄ (3⊃var)←⊂⊃'Susan' 'Mary' 'Annalisa' ⋄ var
 5 4    1  2  3  4   Sue
        5  6  7  8   Maria
        9 10 11 12   Annalisa
 5 4    1  2  3  4    Susan
        5  6  7  8    Mary
        9 10 11 12    Annalisa


On Sat, Mar 4, 2023, at 14:25, Hans-Peter Sorge wrote:
> Hi,
>
> Works as expected
>
> ⊃'Sue' 'Maria' 'Annalisa'
> is an array 3 by 8.
>
> ⊂⊃'Susan' 'Mary' 'Annalisa'
> is an element (⊂) of a 3 by 8  array (⊃'Susan' 'Mary' 'Annalisa' ).
>
> Finally each element in  ⊃'Sue' 'Maria' 'Annalisa' gets assigned an 
> array of  ⊃'Susan' 'Mary' 'Annalisa'
>
> Greetings
> Hans-Peter
>
> Am 04.03.23 um 16:53 schrieb Mr. Sunday:
>> Hi,
>>
>> I have an issue with reassigning an element of a nested array.  Here is an 
>> example.
>>
>> 14535:15a:~% apl --version
>> BUILDTAG:
>> ---------
>>      Project:        GNU APL
>>      Version / SVN:  1.8 / SVN: 1651M
>>      Build Date:     2023-03-02 00:25:07 UTC
>>      Build OS:       Darwin 21.6.0 x86_64
>>      config.status:  default ./configure options
>>      Archive SVN:    1621
>>
>>
>>      var←0 0 0 ⋄ (1⊃var)←5 4 ⋄ (2⊃var)←3 4⍴⍳12 ⋄ (3⊃var)←⊃'Sue' 'Maria' 
>> 'Annalisa' ⋄ var ⋄ (3⊃var)←⊂⊃'Susan' 'Mary' 'Annalisa' ⋄ var
>> ┌→────────────────────────────┐
>> │┌→──┐ ┌→─────────┐ ┌→───────┐│
>> ││5 4│ ↓1  2  3  4│ ↓Sue     ││
>> │└───┘ │5  6  7  8│ │Maria   ││
>> │      │9 10 11 12│ │Annalisa││
>> │      └──────────┘ └────────┘│
>> └ϵ────────────────────────────┘
>> ┌→───────────────────────────────────────────────────────────────────────────────────────────────────────────┐
>> │┌→──┐ ┌→─────────┐ 
>> ┌→──────────────────────────────────────────────────────────────────────────────────────┐│
>> ││5 4│ ↓1  2  3  4│ ↓┌→───────┐ ┌→───────┐ ┌→───────┐ ┌→───────┐ ┌→───────┐ 
>> ┌→───────┐ ┌→───────┐ ┌→───────┐││
>> │└───┘ │5  6  7  8│ │↓Susan   │ ↓Susan   │ ↓Susan   │ ↓Susan   │ ↓Susan   │ 
>> ↓Susan   │ ↓Susan   │ ↓Susan   │││
>> │      │9 10 11 12│ ││Mary    │ │Mary    │ │Mary    │ │Mary    │ │Mary    │ 
>> │Mary    │ │Mary    │ │Mary    │││
>> │      └──────────┘ ││Annalisa│ │Annalisa│ │Annalisa│ │Annalisa│ │Annalisa│ 
>> │Annalisa│ │Annalisa│ │Annalisa│││
>> │                   │└────────┘ └────────┘ └────────┘ └────────┘ └────────┘ 
>> └────────┘ └────────┘ └────────┘││
>> │                   │                                                        
>>                                ││
>> │                   │┌→───────┐ ┌→───────┐ ┌→───────┐ ┌→───────┐ ┌→───────┐ 
>> ┌→───────┐ ┌→───────┐ ┌→───────┐││
>> │                   │↓Susan   │ ↓Susan   │ ↓Susan   │ ↓Susan   │ ↓Susan   │ 
>> ↓Susan   │ ↓Susan   │ ↓Susan   │││
>> │                   ││Mary    │ │Mary    │ │Mary    │ │Mary    │ │Mary    │ 
>> │Mary    │ │Mary    │ │Mary    │││
>> │                   ││Annalisa│ │Annalisa│ │Annalisa│ │Annalisa│ │Annalisa│ 
>> │Annalisa│ │Annalisa│ │Annalisa│││
>> │                   │└────────┘ └────────┘ └────────┘ └────────┘ └────────┘ 
>> └────────┘ └────────┘ └────────┘││
>> │                   │                                                        
>>                                ││
>> │                   │┌→───────┐ ┌→───────┐ ┌→───────┐ ┌→───────┐ ┌→───────┐ 
>> ┌→───────┐ ┌→───────┐ ┌→───────┐││
>> │                   │↓Susan   │ ↓Susan   │ ↓Susan   │ ↓Susan   │ ↓Susan   │ 
>> ↓Susan   │ ↓Susan   │ ↓Susan   │││
>> │                   ││Mary    │ │Mary    │ │Mary    │ │Mary    │ │Mary    │ 
>> │Mary    │ │Mary    │ │Mary    │││
>> │                   ││Annalisa│ │Annalisa│ │Annalisa│ │Annalisa│ │Annalisa│ 
>> │Annalisa│ │Annalisa│ │Annalisa│││
>> │                   │└────────┘ └────────┘ └────────┘ └────────┘ └────────┘ 
>> └────────┘ └────────┘ └────────┘││
>> │                   
>> └ϵ──────────────────────────────────────────────────────────────────────────────────────┘│
>> └ϵϵ──────────────────────────────────────────────────────────────────────────────────────────────────────────┘
>>
>> -- Everyday is Sunday.
>>

-- 
-- Everyday is Sunday.