12.1 Function-calling syntax

This section describes the syntax of Dylan function calls. An explicit function call consists of the operand followed by the arguments enclosed in parentheses and separated by commas. Several other syntactic structures in Dylan are also abbreviations for function calls, including the following:

• Slot references

• References to elements of collections

• Most unary and binary operator calls

• Certain assignment operations

The remainder of this section describes these syntactic forms and the equivalent function calls. Unless otherwise noted, all expressions that make up any of these function calls are evaluated from left to right. (A notable exception is an expression containing the assignment operator, discussed in Section 12.1.6.) The common left-to-right rule makes it easy to understand the order of execution of Dylan code. But it also means that certain syntactic forms that we call equivalent — that is, syntactic forms that generally result in calls to the same function with the same arguments — differ in the order of evaluation of their components. The components can appear in different orders in otherwise equivalent syntactic forms. Usually, the order of evaluation makes no difference, and you can use whichever of the equivalent syntactic forms you find most convenient.