1 files changed, 19 insertions, 0 deletions
diff --git a/transfer/examples/widesnake.tr b/transfer/examples/widesnake.tr
new file mode 100644
index 000000000..23ffac631
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+++ b/transfer/examples/widesnake.tr
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+import bool
+import stoneage
+
+monoid_Bool : sig { zero : Bool; plus : Bool -> Bool -> Bool }
+monoid_Bool = rec
+	        zero = False
+	        plus = \x -> \y -> x && y
+
+isSnake : (A : Tree) -> Tree A -> Bool
+isSnake _ x = case x of
+		Snake -> True
+		_ -> composFold_Tree Bool monoid_Bool ? isSnake x
+
+wideSnake : (A : Cat) -> Tree A -> Tree A
+wideSnake _ x = case x of
+		    Wide y -> let y' : CN = wideSnake ? y
+                               in if isSnake CN y' then Thick y' else Wide y'
+		    _ -> composOp_Tree ? wideSnake x
+