get_first_sum

hugr.tys.get_first_sum(types: list[Type]) → tuple[Sum, list[Type]]

Check the first type in a row of types is a Sum, returning it and the rest.

Parameters:

types – row of types.

Raises:

AssertionError – if the first type is not a Sum.

Example

>>> get_first_sum([UnitSum(3), Qubit])
(UnitSum(3), [Qubit])
>>> get_first_sum([Qubit, UnitSum(3)])
Traceback (most recent call last):
AssertionError: Expected Sum, got Qubit