Ur/Web: demo/constraints.ur annotate

Shorter, more focused error messages about undetermined unification variables

author	Adam Chlipala <adam@chlipala.net>
date	Sat, 29 Oct 2011 17:30:34 -0400
parents	74a090ff296e
children

rev	line source
adamc@773	1 table t : { Id : int, Nam : string, Parent : option int }
adamc@773	2 PRIMARY KEY Id,
adamc@773	3 CONSTRAINT Nam UNIQUE Nam,
adamc@773	4 CONSTRAINT Id CHECK Id >= 0,
adamc@773	5 CONSTRAINT Parent FOREIGN KEY Parent REFERENCES t(Id)
adamc@773	6
adamc@773	7 fun main () =
adamc@773	8 list <- queryX (SELECT * FROM t)
adamc@773	9 (fn r => <xml><tr>
adamc@773	10 <td>{[r.T.Id]}</td>
adamc@773	11 <td>{[r.T.Nam]}</td>
adamc@773	12 <td>{case r.T.Parent of
adamc@773	13 None => <xml>NULL</xml>
adamc@773	14 \| Some id => <xml>{[id]}</xml>}</td>
adamc@773	15 </tr></xml>);
adamc@773	16 return <xml><body>
adamc@773	17 <table>
adamc@773	18 <tr> <th>Id</th> <th>Name</th> <th>Parent</th> </tr>
adamc@773	19 {list}
adamc@773	20 </table>
adamc@773	21
adamc@773	22 <form>
adamc@773	23 <table>
adamc@773	24 <tr> <th>Id:</th> <td><textbox{#Id}/></td> </tr>
adamc@773	25 <tr> <th>Name:</th> <td><textbox{#Nam}/></td> </tr>
adamc@773	26 <tr> <th>Parent:</th> <td><textbox{#Parent}/></td> </tr>
adamc@773	27 <tr> <th/> <td><submit action={add}/></td> </tr>
adamc@773	28 </table>
adamc@773	29 </form>
adamc@773	30 </body></xml>
adamc@773	31
adamc@773	32 and add r =
adamc@773	33 dml (INSERT INTO t (Id, Nam, Parent)
adamc@773	34 VALUES ({[readError r.Id]}, {[r.Nam]},
adamc@773	35 {[case r.Parent of
adamc@773	36 "" => None
adamc@773	37 \| s => Some (readError s)]}));
adamc@773	38 main ()

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