Infiltrate on array mutation

[Qfl3x]

Hello, this is a feature request for something I believe will be interesting to many others.

The idea is to track an array and infiltrate whenever the array is mutated, similar to a debugger. Debuggers work on all variables, but in Julia arrays are the best use-case for this feature.

This feature is most important in the presence of multiple nested functions that pass the same array.

Example: You have a data processing big function that calls multiple other functions. You notice that the output array has NaN's everywhere, and you want to know where exactly did the NaN's start before they propagated to the whole array. In this case, it may be easy to infiltrate at the beginning or end, but within all those nested functions it isn't so easy anymore.

[pfitzseb]

Imo this is out of scope for Infiltrator. You can do this with Debugger.jl already, or by instrumenting all array operations via the AbstractInterpreter interface, or even by redefining them with a conditional @infiltrate statement.