A key value data structure made in haskell just for fun

KeyValue.hs

module Main where

type Pair a = ( [Char], a )

updateValue :: [Char] -> a -> [Pair a] -> [Pair a]
updateValue key value [] = [(key, value)]
updateValue key value [(a, b)]
    | a == key = [(key, value)]
    | otherwise = [(a, b), (key, value)]
updateValue key value ((a, b):xs)
    | a == key = [(key, value)] ++ xs
    | otherwise = [(a, b)] ++ updateValue key value xs

dropValue :: [Char] -> [Pair a] -> [Pair a]
dropValue _ [] = []
dropValue key [(a, b)] = if a == key then [] else [(a, b)]
dropValue key ((a, b):xs) = if a == key then xs else [(a, b)] ++ dropValue key xs

insertPair :: [Char] -> a -> [Pair a] -> [Pair a]
insertPair key value pair = [(key, value)] ++ pair

getValueByKey :: [Char] -> [Pair a] -> Maybe a
getValueByKey _ [] = Nothing
getValueByKey key [(a, b)]
    | a == key = Just b
    | otherwise = Nothing
getValueByKey key ((a, b):xs)
    | a == key = Just b
    | otherwise = getValueByKey key xs

pair1 :: [Pair [Char]]
pair1 = [("hello", "World")]

main :: IO()
main = do
    print(pair1)
    print(insertPair "hello2" "2" pair1)
    print(getValueByKey "hello" pair1)
    print(getValueByKey "hello2" pair1)
    print(updateValue "hello2" "1234" (updateValue "hello" "1234555" pair1))
    print(dropValue "hello" (updateValue "hello" "1234555" (updateValue "hello2" "1234555" pair1)))