Ur/Web: tests/list.ur annotate

Enforce termination of type class instances

author	Adam Chlipala <adamc@hcoop.net>
date	Thu, 26 Mar 2009 15:54:04 -0400
parents	71bafe66dbe1
children	fa2019a63ea4

rev	line source
adamc@196	1 datatype list a = Nil \| Cons of a * list a
adamc@196	2
adamc@196	3 val isNil = fn t ::: Type => fn ls : list t =>
adamc@196	4 case ls of Nil => True \| _ => False
adamc@196	5
adamc@196	6 val show = fn b => if b then "True" else "False"
adamc@196	7
adamc@196	8 val rec delist : list string -> xml body [] [] = fn x =>
adamc@196	9 case x of
adamc@196	10 Nil => <body>Nil</body>
adamc@196	11 \| Cons (h, t) => <body>{cdata h} :: {delist t}</body>
adamc@196	12
adamc@196	13 val main : unit -> page = fn () => <html><body>
adamc@196	14 {cdata (show (isNil (Nil : list bool)))},
adamc@196	15 {cdata (show (isNil (Cons (1, Nil))))},
adamc@196	16 {cdata (show (isNil (Cons ("A", Cons ("B", Nil)))))}
adamc@196	17
adamc@196	18 <p>{delist (Cons ("X", Cons ("Y", Cons ("Z", Nil))))}</p>
adamc@196	19 </body></html>

Mercurial > urweb