This handout covers some changes that have been put in place into the Beginning Student Language since your book was printed.

“Contract” versus “Signature”

In computing, the word contract actually has a technical meaning which is different from the way it is used in the first edition.

Today, when a programmer writes the name of a function and describes the input and output data, he or she is writing a signature. This word is current among programmers using C++, Java, C, Haskell, and many other languages. It is the word we will use.


The first edition tells you to “apply the function to the inputs of the examples” without ever suggesting a mechanism. The second edition provides three mechanisms: check-expect, check-within, and check-error.


For images and animations, we’ll use the second-edition teachpacks 2htdp/image and 2htdp/universe.

Symbols versus Strings

The first edition mentions strings just briefly. The second edition has a lot more stuff on strings. We’ll use strings somewhat more than in the first edition, but not as much as in the second edition.