  We present a composable design scheme for the development of hybrid
quantum/classical algorithms and workflows for applications of quantum
simulation. Our object-oriented approach is based on constructing an expressive
set of common data structures and methods that enable programming of a broad
variety of complex hybrid quantum simulation applications. The abstract core of
our scheme is distilled from the analysis of the current quantum simulation
algorithms. Subsequently, it allows a synthesis of new hybrid algorithms and
workflows via the extension, specialization, and dynamic customization of the
abstract core classes defined by our design. We implement our design scheme
using the hardware-agnostic programming language QCOR into the QuaSiMo library.
To validate our implementation, we test and show its utility on commercial
quantum processors from IBM, running some prototypical quantum simulations.
