create or replace function number_integerp(x) as (
  x = trunc(x)
);

# Return true iff x has the type signature of a Rational
# with the denominator dividing the numerator evenly.
create or replace function rational_integerp(x) as (
   typeof(x) = 'STRUCT(n INTEGER, d INTEGER)'
   and x.n % x.d = 0
);

# Return true if x can be cast to a Complex with
# the imaginary part equal to 0 and an integer real part.
create or replace function complex_integerp(x) as (
  (x::Complex).i = 0 and number_integerp(x.r)
);