Ruby and the interpreter pattern report

This entry is to talk about the article “Language Design and Implementation using Ruby and the Interpreter Pattern” written by our professor Ariel Ortiz. Int his article we read about the SIF, which means S-Expression Interpreter Framework and it is used to demonstrate advanced language concepts and also to demonstrate programming styles. It is a tool for teaching language design and implementation. It is an interpreter based on the Interpreter design pattern.

It is so simple to use, it allows integers, symbols, lists and procedures. Also, we have to mention that Ruby has power and flexibility of dynamic languages, so it is easier to understand. This pattern allows us to write interpreters that can be studied with basic build blocks that this pattern provide us. We can see the different behaviors of trees after being interpreted, and this is called a functional program.

Using an interpreter, the syntax is implemented in the initialize method, it receives an array with all the arguments. Then, validates the syntax and constructs the substrees that corresponds. Also with this method we can analyze the semantic analysis. Here, this method receives a context as a parameter and is called recursively for some or all the child nodes.

One difference that can be noticed is that a compiler generates intermediate code, while an interpreter is a reduced version of a compiler. The Design of patterns is very important to be considered in the process of designing a compiler.