For example:

(1) -> n:TwoDimensionalArray Union ( Integer, Float):=new(2,2,0)

(1)

should display a rectangular array of numbers.

I debugged this a little but hit a wall. In ARR2CAT you find the appropriate conversion operation:

    if R has CoercibleTo(OutputForm) then

      coerce(m:%) ==
        l : List List OutputForm
        l := [[qelt(m,i,j) :: OutputForm _
                  for j in minColIndex(m)..maxColIndex(m)] _
                  for i in minRowIndex(m)..maxRowIndex(m)]
        matrix l

which really looks alright. Note also, that

Union(INT, FLOAT) has KOERCE OUTFORM

(2)

and the operation is not overridden in ARRAY2 or IIARRAY2. But the miracle is, inserting a print("hi")$Lisp in the above operation shows that it actually doesn't get invoked. Somehow it seems to me that rather the following function from HOAGG gets invoked:

       coerce(x:%):OutputForm ==
         bracket
            commaSeparate [a::OutputForm for a in parts x]$List(OutputForm)

which can be seen by looking at:

n:TwoDimensionalArray Union(Integer, Float):=new(2,2,0)

(3)

n::OUTFORM::SEX

   Cannot convert the value from type OutputForm to SExpression .

Status: open => not reproducible