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Type inference
author Adam Chlipala <adamc@hcoop.net>
date Sat, 06 Dec 2008 12:01:12 -0500
parents bacd0ba869e1
children
line wrap: on
line source
table t1 : {A : int, B : string, C : float}
table t2 : {A : float, D : int}

val q1 = (SELECT * FROM t1 ORDER BY t1.A, t1.B)
val q2 = (SELECT * FROM t1 GROUP BY t1.A ORDER BY t1.A, t1.B)
val q3 = (SELECT t1.B FROM t1
        UNION SELECT t1.B FROM t1
        ORDER BY t1.B)

val q4 = (SELECT t1.A, t2.D, t1.A < t2.D AS Lt
        FROM t1, t2
        ORDER BY Lt)
val q5 = (SELECT t1.A, t1.B, t2.D, t1.A < t2.D AS Lt
        FROM t1, t2
        ORDER BY t1.A DESC, Lt ASC, t2.D DESC)


datatype list a = Nil | Cons of a * list a

val r1 : transaction (list string) =
        query q5
        (fn fs acc => return (Cons (fs.T1.B, acc)))
        Nil

val r2 : transaction string =
        ls <- r1;
        return (case ls of
                    Nil => "Problem"
                  | Cons (b, _) => b)

val main : unit -> transaction page = fn () =>
        s <- r2;
        return <html><body>
                {cdata s}
        </body></html>