Arrays and Iterations

Abstract

In Algol 68 arrays are called ‘multiple values’. The most straightforward way of creating a multiple value is to use a ‘row display’. An example of a row display is

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which is a collateral clause all of whose components are of mode int. Collateral clauses have various uses, but when treated as a row display the mode of the above clause is ‘row of int’, otherwise written [ ] int. This, then, introduces ‘rowing’ as a means of developing further modes from the primitive modes. It should be noted that the term ‘rowing’ is applied both to the explicit process of creating a new mode by making a ‘row’, that is, array, of another mode, and to the coercion which in certain circumstances performs the equivalent mode conversion automatically. For the moment it is the explicit creation of rowed modes which we are considering; the coercion equivalent to it will appear later.