Static awareness of value_size where possible

[tpgillam]

Suppose there exists a function value_size, which can take a node. Ideally it would have the following behaviour:

alignment = pulse(Hour(1))

y1 = rand(alignment, 5)
y2 = rand(alignment, 1, 3)

@assert value_size(y1) == (5,)
@assert value_size(y2) == (1, 3)

z1 = wrap(.+)(y1, y2)
@assert value_size(z1) == (5, 3)

y3 = rand(alignment, 3)
wrap(.+)(y1, y3)  # This should throw an exception

This requires an awareness of functions:

• whose output size can be uniquely determined from type & size information of inputs.
• which can be known to throw an exception unless argument types and sizes satisfy some property.