Mercurial > urweb

fun fst [a] [b] (x : a) (y : b) = x
fun snd [a] [b] (x : a) (y : b) = y

fun fact n =
    case n of
        0 => 1
      | _ => n * fact (n - 1)

datatype t =
         A
       | B of {C : int, D : float}
       | E of t * t

fun render x =
    case x of
        A => "A"
      | B {C = n1, D = n2} => "B(" ^ show n1 ^ "," ^ show n2 ^ ")"
      | E (x, y) => "C(" ^ render x ^ "," ^ render y ^ ")"

fun main () =
    s <- source "";
    s' <- source "";
    f <- source (plus 1);
    f2 <- source fst;
    r <- source {A = "x", B = "y"};
    t <- source (E (A, B {C = 10, D = 1.23}));
    ht <- source <xml>Nothing here yet.</xml>;

    return <xml><body>
      <ctextbox source={s}/> <ctextbox source={s'}/><br/><br/>

      Function: <button value="+1" onclick={set f (plus 1)}/>
      <button value="*3" onclick={set f (times 3)}/><br/><br/>

      Function2: <button value="Fst" onclick={set f2 fst}/>
      <button value="Snd" onclick={set f2 snd}/><br/><br/>

      Both: <button value="*3,Snd" onclick={set f (times 3); set f2 snd}/><br/><br/>

      <button value="Echo" onclick={s <- get s; alert s}/>
      <button value="Echo2" onclick={s <- get s; alert s; alert s}/>
      <button value="-" onclick={s <- get s; alert (show (-(readError s : int)))}/>
      <button value="+1" onclick={s <- get s; alert (show (readError s + 1))}/>
      <button value="*3" onclick={s <- get s; alert (show ((readError s) * 3))}/>
      <button value="!" onclick={s <- get s; alert (show (fact (readError s)))}/>
      <button value="f" onclick={s <- get s; f <- get f; alert (show (f (readError s)))}/>
      <button value="+1P" onclick={s <- get s; case read s of
                                                   None => alert "Nada!"
                                                 | Some (n : int) => alert (show (n + 1))}/>

      <button value="f2" onclick={s <- get s; s' <- get s'; f2 <- get f2; alert (f2 s s')}/><br/><br/>

      <button value="A" onclick={r <- get r; alert r.A}/>
      <button value="B" onclick={r <- get r; alert r.B}/><br/><br/>

      <button value="render" onclick={t <- get t; alert (render t)}/><br/><br/>

      <dyn signal={signal ht}/>
      <button value="Set" onclick={s <- get s;
                                   set ht <xml><button value="Dynamic!" onclick={alert s}/></xml>}/>
    </body></xml>
author	Adam Chlipala <adam@chlipala.net>
date	Fri, 24 Dec 2010 18:08:29 -0500
parents	8fe576c0bee9
children