Mercurial > urweb
comparison tests/query.lac @ 243:2b9dfaffb008
Transactions and queries, at source level
| author | Adam Chlipala <adamc@hcoop.net> |
|---|---|
| date | Thu, 28 Aug 2008 14:48:33 -0400 |
| parents | |
| children |
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| 242:cc193f680193 | 243:2b9dfaffb008 |
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| 1 table t1 : {A : int, B : string, C : float} | |
| 2 table t2 : {A : float, D : int} | |
| 3 | |
| 4 datatype list a = Nil | Cons of a * list a | |
| 5 | |
| 6 val q1 = (SELECT * FROM t1) | |
| 7 val r1 : transaction (list {A : int, B : string, C : float}) = | |
| 8 query q1 | |
| 9 (fn fs _ acc => return (Cons (fs.T1, acc))) | |
| 10 Nil | |
| 11 | |
| 12 val r2 : transaction int = | |
| 13 ls <- r1; | |
| 14 return (case ls of | |
| 15 Nil => 0 | |
| 16 | Cons ({A = a, ...}, _) => a) |