Caveats

There are some caveats of working with lazy objects. First, the construction of broadcasted objects and their execution can become separated, requiring more thought and introducing harder-to-debug problems. Second, creating complex Broadcasted objects can increase compile time.

Delayed execution can be confusing

For example:

using LazyBroadcast: lazy_broadcast
a = [0, 0]
b = [0, 0]
c = lazy_broadcast.(a .+ b)
a .= [1, 1]
b .= [1, 1]
nothing

What do you suppose that the result of Base.materialize(c) is now? Let's see:

Base.materialize(c)

2-element Vector{Int64}:
 2
 2

Tada! c is a Base.Broadcasted object that holds pointers to the data a and b, so even though we've since mutated a and b after assigning c, materializing c will yield results for whatever values that a and b contain at that instant. This might be surprising at first, but it's also very powerful. We can think of c as an expression, that holds true for whatever values we put into a and b.

Compilation time

Broadcasted objects are stack-allocated, and therefore increasingly large broadcast expressions may result in increased compilation times.