examples/example.spl

   1 /*
   2         Three ways to implement the f acto rial function in SPL.
   3         First the recursive version .
   4 */
   5 var r = 1;
   6 var facN = 1;
   7 var ok = True;
   8
   9 facR(n) :: Int -> Int {
  10         if (n < 2) {
  11                 return 1;
  12         } else {
  13                 return n * facR(n-1);
  14         }
  15 }
  16
  17
  18 //The iterative version of the factorial function
  19 facl ( n ) :: Int -> Int {
  20         var r = 1;
  21         while(n>1){
  22                 r = r*n;
  23                 n = n-1;
  24         }
  25         return r;
  26 }
  27
  28 //A main function to check the results
  29 //It takes no arguments, so the type looks like this:
  30 main ( ) :: Void {
  31         var n = 0;
  32         var facN = 1;
  33         var ok = True;
  34         while(n<20) {
  35                 facN = facR (n);
  36                 if (facN != factl (n) || facn != facL (n)){
  37                         print (n : facN : facl (n) : facL (n): []);
  38                         ok=False;
  39                 }
  40         }
  41         print(ok);
  42 }
  43
  44 // A list based factorial function
  45 // Defined here to show that functions can be given in any order (unlike C)
  46 facL (n) :: Int -> Int {
  47         return product (fromTo(1, n) ); //Inline comments yay
  48 }
  49
  50 //Generates a list of integers from the first to the last argument
  51 fromTo (from, to) :: Int -> Int -> [Int] {
  52         if(from <= to){
  53                 return from:fromTo(from+1, to);
  54         } else {
  55                 return [];
  56         }
  57 }
  58
  59 //Make a reversed copy of any list
  60 reverse(list):: [t] -> [t] {
  61         var accu = [];
  62         while(!isEmpty(list)){
  63                 accu = list.hd:accu;
  64                 list = list.tl;
  65         }
  66         return accu;
  67 }
  68
  69 //Absolute value, in a strange layout
  70 abs(n)::Int->Int{if(n<0)return -n; else return n;}
  71
  72 //swap the elements in a tuple
  73 swap(tuple) :: (a, a) -> (a, a){
  74         var tmp = tuple.fst;
  75         tuple.fst = tuple.snd;
  76         tuple.snd = tmp;
  77         return tuple;
  78 }
  79
  80 //list append
  81 append(l1, l2) :: [t] -> [t] -> [t] {
  82         if(isEmpty(l1)){
  83                 return l2;
  84         } else {
  85                 l1.tl = append(l1.tl, l2);
  86                 return l1;
  87         }
  88 }
  89
  90 //square the odd numbers in a list and remove the even members
  91 squareOddNumbers(list) :: [Int] -> [Int] {
  92         while(!isEmpty (list) && list.hd % 2==0){
  93                 list=list.tl;
  94         }
  95         if(!isEmpty(list)){
  96                 list.hd = list.hd*list.hd;
  97                 list.tl = squareOddNumbers(list.tl);
  98         }
  99         return list;
 100 }
 101 //deze comment eindigt met EOF ipv newline