Errors

When an error occurs, DrScheme highlights the source of the error, whether it is in the definitions window or the interactions window. For example, typing (/ 1 0) in the interactions window causes that expression to be highlighted (and also produces the error message ``/: division by zero'').

Beware! Don't click the mouse until you have noted which expression was highlighted by DrScheme. If you accientally click and lose the highlighting, try to evaluate the expression again to re-create the error.

Exercise Notes

Exercise 2.3.1 If DrScheme gives the error message ``procedure application: expected procedure'' for the expression (+ (10) 20) make sure that the language level is set to Beginner, as described in Preparing DrScheme. The correct error message is more specific: ``First term after parenthesis is illegal in an application''.