Type object

In addition to several reasonable sentences, we can also derive nonsense like “Computers run cheese” and “This am a lies”. These sentences don’t make semantic sense, but they are syntactically correct because they are of the sequence of subject, verb-phrase, and object. Formal grammars are a tool for syntax, not semantics. We worry about semantics at a later point in the compiling process. In the syntax analysis phase, we verify structure, not meaning.