How to convert real to exact integer in Racket?

Question

How do I convert a value of the form 20.2 into something that (random ...) accepts?

I've tried these:

;; x defined by some earlier maths and of form 20.2

(random (round x))
(random (floor x))

But both return:

random: contract violation
expected: (or/c (integer-in 1 4294967087) pseudo-random-generator?)
given: 20.0

Southeastwardly

Answer 1

These also work, and according to the documentation they're just shorthands for your approach:

(random (exact-round x))
(random (exact-floor x))

Murmur

Answer 2

This article seems to answer the question for Scheme: http://computer-programming-forum.com/40-scheme/674db7a1706960d5.htm

So with code like this I get the result I want:

(random (inexact->exact (round x)))
(random (inexact->exact (floor x)))

Is this the simplest way?

Southeastwardly

In racket, the exact-round and exact-floor functions from racket/math do that. – Memo