Mapped dev-wiki conversion situation for situational awareness

[simantics/platform.git] / docs / Developer / SCL / SCLExamples.md

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+## Eight queens puzzle
+
+Copy the following commands to the SCL console:
+
+```haskell
+> n = 8
+> allPositions = [0..n-1]
+> possibleNextPositions l = allPositions \\ (l + lq + uq)
+    where
+      m = length l
+      lq = [l!i - (m-i) | i <- [0..m-1]]
+      uq = [l!i + (m-i) | i <- [0..m-1]]
+> expandSolution l = do
+      x <- possibleNextPositions l
+      return (l + [x])
+> solve k cur = if k == n
+                then return cur
+                else expandSolution cur >>= solve (k+1)
+> solutions = solve 0 []
+> length solutions
+> repeatString k (s :: String) = sum [s | x <- [1..k]]
+> rowText k = repeatString k "." + "X" + repeatString (n-k-1) "."
+> printSolution (l :: [Integer]) = do
+      printString (repeatString n "-")
+      mapM (printString . rowText) l
+> mapM printSolution solutions
+```
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