An interactive software development environment in one embodiment can interactively provide outputs of execution or evaluation of software entered into the environment prior to compilation of the software and can automatically add one or more error handling expressions that isolate errors from effecting future software. The environment can automatically add the one or more error handling expressions for each line for software or for a set of software to wrap the set to catch and isolate errors. The execution or evaluation of software in the environment can be, for example, by read-evaluate-print-loop functionality provided by the environment.