FWIW, parametric types converted to contracts may change the behavior of the program. It violates a basic axiom of the gradual typing program but it is a pragmatic "thing".
On Nov 17, 2014, at 11:26 PM, Benjamin Greenman <[email protected]> wrote: > I'd like to convert the following typed program into an untyped one that uses > a contract instead of a type signature to protect the member function. > > #lang typed/racket > (struct: (A) Node ([val : A] > [left-tree : (MyTree A)] > [right-tree : (MyTree A)])) > (define-type (MyTree A) (U 'Nil (Node A))) > > (: member (All (A) (-> A (MyTree A) Boolean))) > (define (member x xs) > #t) > > More specifically, can someone help me fill in the blank marked "TODO" below: > > #lang racket > (struct Node (val left-tree right-tree)) > > (define/contract (member x xs) > (parametric->/c [A] TODO) > #t) > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
