[Maxima-bugs] [maxima:bugs] #4350 arrayinfo complains "not an array" when supplied a Lisp array or hash table

[Robert D. <rob...@us...>]

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**[bugs:#4350] arrayinfo complains "not an array" when supplied a Lisp array or hash table**

**Status:** open
**Group:** None
**Labels:** arrayinfo 
**Created:** Mon Aug 19, 2024 08:59 PM UTC by Robert Dodier
**Last Updated:** Mon Aug 19, 2024 08:59 PM UTC
**Owner:** nobody


`arrayinfo` complains "not an array" when its argument is a Lisp array or Lisp hash table. However, when its argument is a symbol which has the Lisp array or hash table bound to it, then `arrayinfo` knows what to do.
```
(%i33) aa: make_array (any, 4);
(%o33)          {Lisp Array: #(NIL NIL NIL NIL)}
(%i34) arrayinfo (aa);
(%o34)                 [declared, 1, [3]]
(%i35) apply (arrayinfo, [aa]);

arrayinfo: {Lisp Array: #(NIL NIL NIL NIL)} is not an array.
 -- an error. To debug this try: debugmode(true);
(%i36) hh: make_array (hashed, 1);
(%o36) 
    {Lisp Array: #<HASH-TABLE :TEST EQUAL :COUNT 1 {1004C322F3}>}
(%i37) hh["foo"]: "bar";
(%o37)                         bar
(%i38) arrayinfo (hh);
(%o38)                [hash_table, 1, foo]
(%i39) apply (arrayinfo, [hh]);

arrayinfo: 
{Lisp Array: #<HASH-TABLE :TEST EQUAL :COUNT 2 {1004C322F3}>}
 is not an array.
 -- an error. To debug this try: debugmode(true);
```
I bumped into this problem in the following context. I have a list of arrays, and I'm trying to call `arrayinfo` on each one. %o41 fails because getting the value of `L[1]` would require calling MEVAL, which, I'm happy to report, `arrayinfo` doesn't call. 

OK so far. The standard workaround is to call `apply(foo, [...])` for an argument-quoting function `foo`. But that doesn't work either, for `arrayinfo`:  
```
(%i40) L: [aa];
(%o40)         [{Lisp Array: #(NIL NIL NIL NIL)}]
(%i41) arrayinfo (L[1]);

arrayinfo: L  is not an array.
            1
 -- an error. To debug this try: debugmode(true);
(%i42) apply (arrayinfo, [L[1]]);

arrayinfo: {Lisp Array: #(NIL NIL NIL NIL)} is not an array.
 -- an error. To debug this try: debugmode(true);
```
The fix is just to handle Lisp array and hash table values in addition to symbols.


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