Mercurial > urweb
annotate tests/newMessage.ur @ 1736:7ec8dab190a7
Better discovery of type class instances from recursive definitions
| author | Adam Chlipala <adam@chlipala.net> |
|---|---|
| date | Wed, 02 May 2012 08:34:50 -0400 |
| parents | |
| children |
| rev | line source |
|---|---|
| adam@1736 | 1 datatype message = NewQuestion of { Id : string} |
| adam@1736 | 2 | Something of {Blah : int} |
| adam@1736 | 3 |
| adam@1736 | 4 fun showMessage (message : message) = |
| adam@1736 | 5 case message of |
| adam@1736 | 6 NewQuestion {Id = a} => a |
| adam@1736 | 7 | Something {Blah = x} => "blah" |
| adam@1736 | 8 |
| adam@1736 | 9 val show_mes = mkShow showMessage |
| adam@1736 | 10 |
| adam@1736 | 11 fun showTwoTuple [a] [b] (_ : show a) (_: show b) = mkShow (fn (two_tuple : {1:a, 2:b}) => |
| adam@1736 | 12 "(" ^ show two_tuple.1 ^ ", " ^ show two_tuple.2 ^ ")" |
| adam@1736 | 13 |
| adam@1736 | 14 ) |
| adam@1736 | 15 val om = show (Something {Blah = 1}, Something {Blah = 2}) |