Type Systems
Explore the role of type systems in programming, including the differences between static and dynamic typing. Understand how types affect function inputs and outputs, and why thorough testing and clear documentation are essential for writing correct and maintainable code. Learn to recognize the limitations of code coverage metrics and strategies for dealing with untestable code scenarios.
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Dealing with different languages
When we refer to something like 42 in code, is that a number, a string, or what? If you have a function like factorial(n), what kind of thing is supposed to go into it, and what’s supposed to come out? The type of elements, functions, and expressions is essential. How a language deals with types is called its type system.
The type system can be an important tool for writing correct programs. For example, in Java, we could write a method like this:
In this case, both the learner and the compiler can easily deduce that factorial() should take a number and return a number. Java is statically typed because it checks types when code is compiled. Trying to pass in a string simply won’t compile. ...