The Wolfram Language can represent not only data and programs, but also the execution history of programs, as symbolic expressions—which can be displayed, manipulated, and analyzed using the full power of the Wolfram Language.

Trace — generate symbolic execution history filtered with various criteria

TracePrint — print whenever execution-history criteria are satisfied

TraceDialog — enter a dialog whenever execution-history criteria are satisfied

TraceScan — apply any function whenever execution-history criteria are satisfied

Stack — full or filtered symbolic version of the current evaluation stack

StackBegin  ▪  StackInhibit  ▪  StackComplete

Assert — give an assertion to be checked when code is executed