3_a_2: Add solution

1 files changed, 25 insertions, 0 deletions

diff --git a/ch03/3_a_2.hs b/ch03/3_a_2.hs
new file mode 100644
index 0000000..42282e7
--- /dev/null
+++ b/ch03/3_a_2.hs
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+-- Define a tree type that has only one constructor, like our Java
+-- example. Instead of the Empty constructor, use the Maybe type to refer to a
+-- node's children.
+
+-- The assignment doesn't explicitly specify whether it should be possible to
+-- create an empty tree at the root level, so this tree type doesn't support
+-- that.
+
+data Tree a = Node a (Maybe (Tree a)) (Maybe (Tree a))
+              deriving (Show)
+
+
+--          parent
+--            /\
+--           /  \
+-- left child   right child
+--                  /
+--                 /
+--            left child
+
+simpleTree = Node "parent" (Just (Node "left child" Nothing
+                                                    Nothing))
+                           (Just (Node "right child" (Just (Node "left child" Nothing
+                                                                              Nothing))
+                                                     Nothing))