initialStackingWithNSubejcts.js

function subjectsReducer(state = initialSubjectsState(), action = {}){
    switch(action.type){
        case LOAD_SUBJECTS_RESULTS:
            return Object.assign({}, state, { list: subjectsToHash(action.subjects) });
    }
    return state;
}

function subjectsToHash(subjects){
    let hash = {};
    subjects.forEach(s => hash[s._id] = s);
    return hash;
}