Chapter 18 Expressions
Learning objectives:
- Understand the idea of the abstract syntax tree (AST).
- Discuss the data structures that underlie the AST:
- Constants
- Symbols
- Calls
- Explore the idea behind parsing.
- Explore some details of R’s grammar.
- Discuss the use or recursive functions to compute on the language.
- Work with three other more specialized data structures:
- Pairlists
- Missing arguments
- Expression vectors