This paper explores the difference between flexibility of design and flexibility of construction, and how this affects programming and programming languages. Including the right amount of flexibility in the design of a program is a delicate task best suited to humans. The flexibility of construction, on the other hand, is defined by the programming language that is used. We define what a programming language should offer in support of flexibility of construction and explore the advantages of having this flexibility of code. We conclude with a short taste of TOM, an object-oriented programming language that has been developed to provide flexibility of code.

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