Lab 18 Instructions #

Reminders #

While students are coming into class, feel free to go ahead and download the lab materials in preparation for the start of the lab proper. (But please wait until you’re instructed before beginning work on the lab.)
Get out paper and pencil. You’ll need it for this lab.
For the upcoming labs, especially lab 19, we especially recommend downloading the repo early and looking over the files to get familiar with what you’ll be doing with your lab group in the lab sessions.
Remember, class on April 18 and 23 are the final two of the oh-so-scarce CS51 lectures. They will be at 12:45 in the SEC 1.321 lecture hall.

Here is the semantic rule ($R_{+}$) for the binary addition operator from Figure 19.4 (lexical environment semantics with environment and store):

Today’s puzzle concerns the following four variants of the rule: