ENH: print generated code

[albop]

With the new smarter functions, it has become harder to inspect the generated code (unless I missed smthg).
Maybe the FunctionFactory object could hold an option to print the code when generated. Or maybe there is a better way ?

[sglyon]

Ahh yes this is true.

So none the code that actually evaluates the user's equations will actually be printed anymore, because it isn't even generated until the user asks for it at runtime.

One thing you can do still is println(Dolang.build_function(ff, Der{N})) to see the whole function for derivative order N.

Does that work?