 The language makes a distinction between read-time, compile-time, load-time, and run-time, and allows user code to also make this distinction to perform the wanted type of processing at the wanted step.Some special operators are provided to especially suit interactive development; for instance, codice_86 will only assign a value to its provided variable if it wasn't already bound, while codice_87 will always perform the assignment.This distinction is useful when interactively evaluating, compiling and loading code in a live image.