© Thomas Mailund 2017

Thomas Mailund, Metaprogramming in R, 10.1007/978-1-4842-2881-4_3

3. Expressions and Environments

Thomas Mailund

(1)Aarhus N, Denmark

This chapter digs deeper into how environments work and how you can evaluate expressions in different environments. Understanding how environments are chained together helps you understand how the language finds variables, and being able to create, manipulate, and chain together environments when evaluating expressions is a key trick for metaprogramming.


You can consider everything that is evaluated in R to be an expression. Every statement you have in your programs is also an expression that evaluates to some value (which, of course, might be NULL). This includes control structures ...

Get Metaprogramming in R: Advanced Statistical Programming for Data Science, Analysis and Finance now with the O’Reilly learning platform.

O’Reilly members experience live online training, plus books, videos, and digital content from nearly 200 publishers.