#lang typed-scheme (require scheme/math typed/test-engine/scheme-tests) (define-struct: circle ({radius : Number})) (: circle-area (circle -> Number)) (check-within (+ 1 2.14) pi .1) (check-range 2 1 3) (check-member-of 'a 'b 'c 'd 'a 'z) (check-error (error "fail") "fail") (define (circle-area c) (* pi (circle-radius c) (circle-radius c))) (test)