I am trying to define a procedure that takes an integer and returns its representation in Church numerals. Could any one please help me figure out the mistake I am making? The following code it's what I have been able to do so far.
(define succ
(lambda (cn)
(lambda (f)
(lambda (x)
(f ((cn f) x))))))
(define (n->cn n)
(if (= n 0)
zero
(succ (n->cn (lambda (x) (- x 1))))))
When I run the test:
(test (num->cn 3) three)
I am getting the following error:
exception (num->cn 3) at line 107
expected: <no-expected-value>
=: contract violation
expected: number?
given: #<procedure:...ad/racket-file.rkt:99:21>
argument position: 1st
other arguments...:
0
It seems it's expecting a number? but a procedure is given. Which I think matches the intention of the procedure? Thanks for your help and comments for a newbie.
The argument to n->ch should be a number, not a procedure:
(define (n->cn n)
(if (= n 0)
zero
(succ (n->cn (- n 1)))))