Such as this, submitted by Torsten Grust:
(define-record-procedures-parametric stream_ stream-of
make-stream
stream?
(stream-head stream-tail))
(define stream
(lambda (t)
(signature (stream-of t (-> (stream t))))))
(: from (number -> (stream number)))
(define from
(lambda (n)
(make-stream n (lambda () (from (+ n 1))))))
(: foo (stream number))
(define foo (from 1))
The problem was that the arbitaries got evaluated too eagerly.
