int64_float64_when(?Int64:integer, ?Float64:float) is det[private]
Reinterpret-cast between uint64 and float64. For example, int64_float64(3ff0000000000000,1.0).

This predicate delays until either Int64 or Float64 is sufficiently instantiated.

There is also a non-delayed uint64_int64/2

Int64- 64-bit unsigned integer
Float64- 64-bit float
- Type,Domain if Value or Codes are of the wrong type or out of range.
- instantiation error if both Value and Codes are uninstantiated.