0 QTRS
app(app(map, f), nil) → nil app(app(map, f), app(app(cons, x), xs)) → app(app(cons, app(f, x)), app(app(map, f), xs)) app(app(app(comp, f), g), x) → app(f, app(g, x)) app(twice, f) → app(app(comp, f), f)