Simple scalar

In nested array theory, a simple scalar is an array encoding data from one of the languages fundamental data types such as a number or character. A simple scalar is defined to be a scalar whose only element is itself. All nested APLs specify that simple scalars float, that is, a scalar array containing only a simple scalar is identical to that simple scalar. Because of this property, all arrays which are both simple and scalar are simple scalars.

Simple scalars are the only arrays with depth 0. An array consisting only of simple scalars therefore has depth 1; such arrays are called simple.