Learning Truffle DSL

Truffle defines a Domain-Specific Language (DSL) based on the Java annotation processor. The language developer has to write a lot of boilerplate code to manage the states of the specializations. To appreciate how Truffle DSL makes a programmer's life easy, let's take a quick example:

c = a + b

As we discussed earlier in this chapter, in AST, every operation and operand is represented as a node. In Truffle, it is a Java class derived from com.oracle.truffle.api.nodes.Node. To understand the need for a DSL, let's oversimplify the implementation of AST for the preceding expression.

Since we are looking at dynamically typed languages, a and b can be any type. We need an expression node that should implement an execute method, which checks for all the possible types for a and b. We will have to write logic something like this:

Figure 6.5 – Guard checks for implementing specialization – flow chart

In the...