The HoTT reals coincide with the Euclidean reals

Escard\'o and Simpson defined a notion of interval object by a universal property in any category with binary products. The Homotopy Type Theory book defines a higher inductive-inductive notion of reals, and suggests that the interval in this type may satisfy this universal property. We show that this is indeed the case in the category of sets of any universe. We also show that the type of HoTT reals is the smallest Cauchy complete subset of the Dedekind reals containing the rationals.