Add back peano numbers

This commit is contained in:
Yiyun Liu 2025-05-11 17:55:50 -04:00
parent 212cbdbceb
commit eb4291f6a0
2 changed files with 32 additions and 15 deletions

View file

@ -23,9 +23,10 @@
(: tm-pair Term)
(define tm-pair `(λ (λ (λ ,(tm-app '(var 0) '(var 2) '(var 1))))))
;; (define tm-fix
;; (let ([g (tm-abs (tm-app (tm-var 1) (tm-app (tm-var 0) (tm-var 0))))])
;; (tm-abs (tm-app g g))))
(: tm-fix Term)
(define tm-fix
(let ([g (tm-abs (tm-app (tm-var 1) (tm-app (tm-var 0) (tm-var 0))))])
(tm-abs (tm-app g g))))
(: tm-zero Term)
(define tm-zero tm-snd)
@ -51,10 +52,23 @@
(tm-suc (tm-nat (- n 1)))
tm-zero))
;; (define (tm-pnat n)
;; (if (positive? n)
;; `(succ ,(tm-pnat (- n 1)))
;; 'zero))
(: tm-const Term)
(define tm-const tm-fst)
(: tm-loop Term)
(define tm-loop
(let ([g (tm-abs (tm-app (tm-var 0) (tm-var 0)))])
(tm-app g g)))
(: tm-nat-to-pnat Term)
(define tm-nat-to-pnat
(tm-abs (tm-app (tm-var 0) (tm-abs '(succ (var 0))) 'zero)))
(: tm-pnat (-> V Term))
(define (tm-pnat n)
(if (positive? n)
`(succ ,(tm-pnat (- n 1)))
'zero))
;; (define (tm-ifz a b c)
;; `(if-zero ,a ,b ,c))
@ -75,6 +89,8 @@
(check-equal? (normalize `(app (app (app ,tm-pair ,tm-id) ,tm-fst) ,tm-fst)) tm-id)
(check-equal? (normalize (tm-app tm-snd (tm-app tm-pair tm-id tm-fst) tm-fst)) tm-fst)
(check-equal? (normalize (tm-add (tm-nat 499) (tm-nat 777))) (normalize (tm-add (tm-nat 777) (tm-nat 499))))
(check-equal? (normalize (tm-app tm-const (tm-nat 0) tm-loop)) (normalize (tm-nat 0)))
(check-equal? (normalize (tm-app tm-nat-to-pnat (tm-nat 10))) (tm-pnat 10))
;; (check-equal? (normalize (tm-mult (tm-nat 3) (tm-nat 2))) (normalize (tm-nat 6)))
;; (check-equal? (normalize (tm-mult (tm-nat 11) (tm-nat 116))) (normalize (tm-nat 1276)))
;; (check η-eq? (normalize (tm-add (tm-nat 499) (tm-nat 777))) (normalize (tm-add (tm-nat 777) (tm-nat 499))))