Theano/Theano — pull request #111 by jaberg (2011-10-10 21:27:48+00:00)
Title: adding callback argument to VM_Linker

The proposed callback argument to VM_Linker is documented as follows:

callback - a callable object to call after each call to a thunk within
the virtual machine. It will be called with four arguments called
'node', 'thunk', 'storage_map', and 'compute_map'.

The purpose of such a callback is to inspect the values computed the virtual machine as they are computed, rather than only at the end. This is especially useful for catching problems that later prevent the VM from reaching the end of the function.