KrylovKit.jl v0.7 now depends on and uses VectorInterface.jl to define the vector-like behavior of the input vectors, rather than some minimal set of methods from Base and LinearAlgebra. The advantage is that many more types from standard Julia are now supported out of the box, such as nested vectors or immutable objects such as tuples. For custom user types for which the old set of required methods was implemented, there are fallback definitions of the methods in VectorInferace.jl such that these types should still be supported, but this might result in warnings being printed. In that respect, this new version is potentially weakly breaking. It is recommend to implement full support for at least the methods in VectorInterface without bang (zerovector, add, scale, inner) and with double bang (add!!, scale!!), where the latter set of methods can use in-place mutation if your type supports this behavior.
In particular, tuples are now supported:
julia> values, vectors, info = eigsolve(t -> cumsum(t) .+ 0.5 .* reverse(t), (1,0,0,0));
julia> values
4-element Vector{ComplexF64}:
2.5298897746721303 + 0.0im
0.7181879189193713 + 0.4653321688070444im
0.7181879189193713 - 0.4653321688070444im
0.03373438748912972 + 0.0im
julia> vectors
4-element Vector{NTuple{4, ComplexF64}}:
(0.25302539267845964 + 0.0im, 0.322913174072047 + 0.0im, 0.48199234088257203 + 0.0im, 0.774201921982351 + 0.0im)
(0.08084058845575778 + 0.46550907490257704im, 0.16361072959559492 - 0.20526827902633993im, -0.06286027036719286 - 0.6630573167350086im, -0.47879640378455346 - 0.18713670961291684im)
(0.08084058845575778 - 0.46550907490257704im, 0.16361072959559492 + 0.20526827902633993im, -0.06286027036719286 + 0.6630573167350086im, -0.47879640378455346 + 0.18713670961291684im)
(0.22573986355213632 + 0.0im, -0.5730667760748933 + 0.0im, 0.655989711683001 + 0.0im, -0.4362493350466509 + 0.0im)
Shout-out to @lkdvos for making this happen!