A program code execution is monitored. Variable type and value information the one or more variables in the program code take during the execution of the program code are stored, and compiled over multiple execution of the program code as historical run-time execution traces. A code editor user interface may present the historical run-time execution traces for inspection, whether or not the program code is currently executing. Statistical properties associated with the variable type and value information may be computed. Future variable type and value the one or more variables might take during future execution of the program code may be predicted.