Larceny has six representations for numbers: fixnums are small, exact integers; bignums are unlimited-precision exact integers; ratnums are exact rationals; flonums are inexact rationals; rectnums are exact complexes; and compnums are inexact complexes.
You can read more about the number representations here.
(fixnum? obj) => boolean
(bignum? obj) => boolean
(ratnum? obj) => boolean
(flonum? obj) => boolean
(rectnum? obj) => boolean
(compnum? obj) => boolean
These predicates test whether an object is a number of a particular representation and return #t if so, #f if not.
(random limit) => exact integer
Returns a pseudorandom nonnegative exact integer in the range 0 through limit-1.