Added haskell versions (parameterized by CLI argument)

koka_bench/haskell/nqueens.hs

@@ -0,0 +1,44 @@
+
+import System.Environment
+
+data List a = Nil | Cons !a !(List a)
+
+len xs
+  = len' xs 0
+
+len' xs acc
+  = case xs of
+      Nil -> acc
+      Cons _ t -> len' t $! (acc+1)
+
+safe queen diag xs
+  = case xs of
+      Nil      -> True
+      Cons q t -> queen /= q && queen /= q + diag && queen /= q - diag && safe queen (diag + 1) t
+
+appendSafe k soln solns
+  = if (k <= 0)
+     then solns
+     else if safe k 1 soln
+           then appendSafe (k-1) soln (Cons (Cons k soln) solns)
+           else appendSafe (k-1) soln solns
+
+
+extend n acc solns
+  = case solns of
+      Nil            -> acc
+      Cons soln rest -> extend n (appendSafe n soln acc) rest
+
+find_solutions n k
+  = if k == 0
+     then Cons Nil Nil
+     else extend n Nil (find_solutions n (k-1))
+
+-- fst_solution n = head (find_solutions n n)
+
+queens n
+  = len (find_solutions n n)
+
+main = do
+  [arg] <- getArgs
+  print (queens (read arg))