Actions: The Second Ingredient of a Program

Abstract

In this chapter the second ingredient of a program namely “actions” that programmers use to manipulate data for solving real-world problems are introduced. Actions are transformed into machine instructions, which are then decoded and executed by the CPU. After a brief discussion on the purpose and the scope of actions, different action types are introduced. An important part of Chap. 3 is devoted to expressions and their evaluation: regarding this, Church–Rosser property, side-effects and Dikstra’s “Shunting Yard Algorithm”, which is the most common expression evaluation method, are presented. The chapter also talks about the different operators that a programmer can use in expressions, the actions that can be used for controlling the flow of the program (i.e., conditionals) and the actions that can be reused again (i.e., functions). Like other chapters, the discussions and the presentations are supported by the case studies and examples in Python.