R Programming By Example

The interpreter and the console

As I mentioned earlier, R is an interpreted language. When you enter an expression into the R console or execute an R script in your operating system's terminal, a program called the interpreter parses and executes the code. Other examples of interpreted languages are Lisp, Python, and JavaScript. Unlike C, C++, and Java, R doesn't require you to explicitly compile your programs before you execute them.

All R programs are composed of a series of expressions. The interpreter begins by parsing each expression, substituting objects for symbols where appropriate, evaluates them, and finally return the resulting objects. We will define each of these concepts in the following sections, but you should understand that ...