λ x : word64 * word64 * word64 * word64,
Interp-η
(λ var : Syntax.base_type → Type,
 λ '(x5, x6, x4, x2)%core,
 uint64_t x7 = (x6 | x5);
 uint64_t x8 = (x4 | x7);
 uint64_t x9 = (x2 | x8);
 return x9)
x
     : word64 * word64 * word64 * word64 → ReturnType uint64_t