Mercurial > urweb
view demo/refFun.ur @ 1619:15e0c935c91b
Catching integer divisions by zero
author | Adam Chlipala <adam@chlipala.net> |
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date | Sat, 03 Dec 2011 09:44:07 -0500 |
parents | 1a317a707d71 |
children |
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functor Make(M : sig type data val inj : sql_injectable data end) = struct type ref = int sequence s table t : { Id : int, Data : M.data } PRIMARY KEY Id fun new d = id <- nextval s; dml (INSERT INTO t (Id, Data) VALUES ({[id]}, {[d]})); return id fun read r = o <- oneOrNoRows (SELECT t.Data FROM t WHERE t.Id = {[r]}); case o of None => error <xml>You already deleted that ref!</xml> | Some r => return r.T.Data fun write r d = dml (UPDATE t SET Data = {[d]} WHERE Id = {[r]}) fun delete r = dml (DELETE FROM t WHERE Id = {[r]}) end