annotate tests/option.ur @ 256:e52243e20858

'eq' type class
author Adam Chlipala <adamc@hcoop.net>
date Sun, 31 Aug 2008 15:15:41 -0400
parents 71bafe66dbe1
children 77a28e7430bf
rev   line source
adamc@198 1 datatype option a = None | Some of a
adamc@198 2
adamc@198 3 val none_Hi : option string = None
adamc@198 4 val some_Hi = Some "Hi"
adamc@198 5 val none_some_Hi : option (option string) = None
adamc@198 6 val some_some_Hi = Some some_Hi
adamc@198 7
adamc@198 8 val show = fn x => case x of None => "None" | Some x => x
adamc@198 9
adamc@198 10 val show2 = fn x => case x of None => "None'" | Some x => show x
adamc@198 11
adamc@198 12 val page = fn x => <html><body>
adamc@198 13 {cdata (show x)}
adamc@198 14 </body></html>
adamc@198 15
adamc@198 16 val page2 = fn x => <html><body>
adamc@198 17 {cdata (show2 x)}
adamc@198 18 </body></html>
adamc@198 19
adamc@198 20 val main : unit -> page = fn () => <html><body>
adamc@198 21 <li><a link={page none_Hi}>None1</a></li>
adamc@198 22 <li><a link={page some_Hi}>Some1</a></li>
adamc@198 23 <li><a link={page2 none_some_Hi}>None2</a></li>
adamc@198 24 <li><a link={page2 some_some_Hi}>Some2</a></li>
adamc@198 25 </body></html>