Y may be any array.  R is a simple numeric scalar.

Tally returns the number of major cells of Y. See Cells and Sub-arrays.

This can also be expressed as the length of the leading axis or 1 if Y is a scalar. Tally is equivalent to the function {⍬⍴(⍴⍵),1}.

Examples

      ≢2 3 4⍴⍳10
2
      ≢2
1
      ≢⍬
0

Note that ≢V is useful for returning the length of vector V as a scalar. (In contrast, ⍴V is a one-element vector.)