|
adamc@315
|
1 datatype list a = Nil | Cons of a * list a
|
|
adamc@315
|
2
|
|
adamc@315
|
3 fun isNil (t ::: Type) (ls : list t) : bool =
|
|
adamc@315
|
4 case ls of
|
|
adamc@315
|
5 Nil => True
|
|
adamc@315
|
6 | Cons _ => False
|
|
adamc@315
|
7
|
|
adamc@316
|
8 fun append (t ::: Type) (ls1 : list t) (ls2 : list t) : list t =
|
|
adamc@315
|
9 case ls1 of
|
|
adamc@315
|
10 Nil => ls2
|
|
adamc@315
|
11 | Cons (x, ls1') => Cons (x, append ls1' ls2)
|
|
adamc@315
|
12
|
|
adamc@317
|
13 fun pairAppend (t1 ::: Type) (t2 ::: Type) (ls1 : list (t1 * t2)) (ls2 : list (t1 * t2)) : list (t1 * t2) =
|
|
adamc@317
|
14 case ls1 of
|
|
adamc@317
|
15 Nil => ls2
|
|
adamc@317
|
16 | Cons (x, ls1') => Cons (x, pairAppend ls1' ls2)
|
|
adamc@317
|
17
|
|
adamc@315
|
18 fun delist (ls : list string) : xml body [] [] =
|
|
adamc@315
|
19 case ls of
|
|
adamc@315
|
20 Nil => <body>Nil</body>
|
|
adamc@316
|
21 | Cons (h, t) => <body>{cdata h} :: {delist t}</body>
|
|
adamc@315
|
22
|
|
adamc@317
|
23 fun pairDelist (ls : list (string * int)) : xml body [] [] =
|
|
adamc@317
|
24 case ls of
|
|
adamc@317
|
25 Nil => <body>Nil</body>
|
|
adamc@317
|
26 | Cons ((s, n), t) => <body>({cdata s}, {cdata (show _ n)}) :: {pairDelist t}</body>
|
|
adamc@317
|
27
|
|
adamc@315
|
28 val ls = Cons ("X", Cons ("Y", Cons ("Z", Nil)))
|
|
adamc@316
|
29 val ls' = Cons ("A", Cons ("B", Nil))
|
|
adamc@315
|
30
|
|
adamc@317
|
31 val pls = Cons (("X", 1), Cons (("Y", 2), Cons (("Z", 3), Nil)))
|
|
adamc@317
|
32 val pls' = Cons (("A", 1), Cons (("B", 2), Nil))
|
|
adamc@317
|
33
|
|
adamc@315
|
34 fun main () : transaction page = return <html><body>
|
|
adamc@315
|
35 {if isNil ls then <body>It's Nil.</body> else <body>It's not Nil.</body>}
|
|
adamc@316
|
36
|
|
adamc@316
|
37 <p>{delist (append ls' ls)}</p>
|
|
adamc@317
|
38
|
|
adamc@317
|
39 <p>{pairDelist (pairAppend pls' pls)}</p>
|
|
adamc@315
|
40 </body></html>
|
