Prototype: Difference between revisions

The prototype is used when an array is expanded or when empty elements are inserted in some other way. [[Take]] and [[Expand]] on a [[character]] array produce an array with spaces, because <code>' '</code> is the prototype of a character array:

The [[Rank operator]] combines its left operand's result cells by extending them to a common shape like [[Mix]] does. Numeric vectors of different lengths will be expanded with <code>0</code>, the prototype for a simple numeric array.

An array's prototype is based on its first element, so the array <code>a</code> below has a simple numeric prototype, as does any prefix of <code>a</code>. This property even applies to empty arrays: the expression <code>0 ↑ a</code> results in an empty array with the same prototype as <code>a</code>.