Prism::Node#type

Sometimes you want to check an instance of a node against a list of classes to see what kind of behavior to perform. Usually this is done by calling [cls1, cls2].include?(node.class) or putting the node into a case statement and doing case node; when cls1; when cls2; end. Both of these approaches are relatively slow because of the constant lookups, method calls, and/or array allocations.

Instead, you can call type, which will return to you a symbol that you can use for comparison. This is faster than the other approaches because it uses a single integer comparison, but also because if you’re on CRuby you can take advantage of the fact that case statements with all symbol keys will use a jump table.