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import Data.Maybe
-- Fra lec5
valid :: (Integral a, Ord a) => [(a, b)] -> Bool
valid = recur empty
where recur _ [] = True
recur known (pair:rest) =
if key `member` known
then False
else recur (insert key known) rest
where key = fst pair
-- TODO, case where key is not in is unhandled
lookup' :: (Integral a, Ord a) => [(a, b)] -> a -> b
lookup' (pair:rest) key = if (fst pair) == key
then (snd pair)
else lookup' rest key
-- I dont see how findfun and lookup are not the same
findfun = lookup'
data LTree = LLeaf String | LNode LTree LTree
data LTreeRoot = LTreeRoot LTree Float
treemerge :: LTreeRoot -> LTreeRoot -> LTreeRoot
treemerge (LTreeRoot ta la) (LTreeRoot tb lb) = LTreeRoot (LNode ta tb) (la + lb)
data Bit = Zero | One
instance Show Bit where
show Zero = "0"
show One = "1"
createBitList :: String -> Maybe [Bit]
createBitList [] = Just []
createBitList (c:rest) | c == '0' = createBitList rest >>= Just . (:) Zero
| c == '1' = createBitList rest >>= Just . (:) One
| otherwise = Nothing
maketable :: LTree -> [([Bit], String)]
maketable = recur []
where recur prefix (LLeaf val) = [(reverse prefix, val)]
recur prefix (LNode left right) =
recur (Zero : prefix) left ++
recur (One : prefix) right
testTree = LNode (LLeaf "Hej") (LNode (LLeaf "Med") (LLeaf "Dig"))
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