Changed dderiv to be closer to the untyped version.

This commit is contained in:
Vincent St-Amour 2010-06-23 14:50:33 -04:00
parent b345d5f0f0
commit a14c31a1de

View File

@ -42,10 +42,9 @@
(: put (Symbol Symbol ((Listof Deriv) -> Deriv) -> Void))
(define (put sym d what)
(set! pg-alist (cons (cons sym what) pg-alist)))
(: get (Symbol Symbol -> (U ((Listof Deriv) -> Deriv) #f)))
(: get (Symbol Symbol -> ((Listof Deriv) -> Deriv)))
(define (get sym d)
(cond ((assq sym pg-alist) => cdr)
(else #f)))
(cdr (assert (assq sym pg-alist))))
(define-type Deriv (Rec Deriv (U Number
Symbol