gftype.py

from pygraphblas import Type, Monoid, Semiring, binary_op

class BF_Tuple3(Type):

    identity = (float('inf'),  # sum of edge lengths
                UINT64_MAX,    # parent of ith vertex
                UINT64_MAX)    # number of edges from s to i

    @binary_op
    def min(self, other):
        ...

    @binary_op
    def plus(self, other):
        ...

    min_monoid = Monoid(min, identity)
    min_plus = Semiring(min_monoid, plus)