a11/mart/skeleton11.icl

   1 module skeleton11
   2
   3 import StdEnv
   4
   5 :: Prog :== [Instr]
   6
   7 :: Instr = Write Expr
   8
   9 :: Expr = Int   Int
  10         | Plus  Expr Expr
  11         | Times Expr Expr
  12         | Read
  13
  14 possibleResults :: [Prog] -> [Int]
  15 possibleResults x = produce (map (map (\(Write x).eval x)) x) 0
  16
  17 produce :: [[Int->Int]] Int -> [Int]
  18 produce x i
  19 | all (isEmpty) x = [i]
  20 = flatten [produce (updateAt idx ys x) (y i)\\(idx, [y:ys])<-zip2 [0..] x]
  21
  22 eval :: Expr Int -> Int
  23 eval (Int i) s = i
  24 eval (Plus e1 e2) s = eval e1 s + eval e2 s
  25 eval (Times e1 e2) s = eval e1 s * eval e2 s
  26 eval Read s = s
  27
  28
  29 prog0 = [Write (Int 12), Write (Plus Read (Int 1))]
  30 prog1 = [Write (Times Read (Int 2))]
  31 test0 = [prog0]
  32 test1 = [prog0, prog1]
  33
  34 Start = (
  35         possibleResults test0,
  36         possibleResults test1)