Expression based virtual products

[jeandet]

The idea would be to allow the following pseudo code:

import speasy as spz
from speasy import symbolic as sym

a1s, b1s, c1s = sym.resample([spz.inventory.a, spz.inventory.b, spz.inventory.c], "1s")

my_expression = 10 * a1s / (b1s*c1s)

sym.register_virtual_product( "/some/path/in/inventory", my_expression)
 

Where sym.resample and my_expression just yield the expression without any computation. Using SymPy to create expressions and Numba as backend might be the way to go.