I ended up putting the wrong reply here to this frament, sorry about that:
> > This is generally a false statement. ... how lazy evaluation can share chunks (bits of compute)
> It would be true in a pure functional language, and is only false to the extent that a real-world "functional" languages actually have some imperative features.
What I had intended to say was that, yes, this is the sort of feature of functional languages I was talking about. In a true (perhaps theoretical) functional programming language, all functions are pure, so you can arbitrarily reorder function calls (relative to other calls of the same function and to calls to other functions) and this cannot possibly have an effect on the meaning of the program. You can even coalesce multiple calls to the same function with the same parameters.
As I'm sure you realise, this can't work for functions that have side effects e.g. reading bytes from a socket. Again, these are things that can happen for functions, including callbacks, in imperative programming languages (or the imperative bit of mixed or mostly-functional programming langauges).
> > This is generally a false statement. ... how lazy evaluation can share chunks (bits of compute)
> It would be true in a pure functional language, and is only false to the extent that a real-world "functional" languages actually have some imperative features.
What I had intended to say was that, yes, this is the sort of feature of functional languages I was talking about. In a true (perhaps theoretical) functional programming language, all functions are pure, so you can arbitrarily reorder function calls (relative to other calls of the same function and to calls to other functions) and this cannot possibly have an effect on the meaning of the program. You can even coalesce multiple calls to the same function with the same parameters.
As I'm sure you realise, this can't work for functions that have side effects e.g. reading bytes from a socket. Again, these are things that can happen for functions, including callbacks, in imperative programming languages (or the imperative bit of mixed or mostly-functional programming langauges).