To interrupt the running of your code, find a place in your code where you want to gather information. Then, specify a breakpoint by adding the message halt or the expression self halt.

For example, evaluate the following code in a Workspace with the Execute command:

A debugger opens, showing the error message '(ExHalt) A halt has occurred.' The top of the stack has the following messages:

Select OrderedCollection(Object)>>#halt in the message stack and inspect self in the list of variables. Notice that the ordered collection exists but contains no entries.