wrong reduce-by-key interface about pico

[cmisale]

why K?

[mdrocco]

This is the signature of the class, K is used within the body (e.g., passed when instantiating the FF node)

[cmisale]

I don't understand why the input type is K in the template and V in the constructor

[cmisale]

I propose
template
class ReduceByKey(std::function<V(V &, V &)>);

I prefer template because it would be easier to "match" the datatype with the operator right before the ReduceByKey. I think it goes better with the flow of data types.
What do you think?
Of course please point out all the problems I don't see.
@droccom @FalkenRambaldi

[cmisale]

I don't know what I did, but the thing was supposed to be the following:

template <typename KV> 
class ReduceByKey(std::function<V(V &, V &)>);

[mdrocco]

I agree, let me try this way.