module ValuesBy where

import Data.List

data Map key value = Map[(key,value)]

get :: Eq k => k -> Map k v -> Maybe v
get k mapt @ (Map map') = let index = contains k mapt
             in if index >= 0 then (Just (snd (map' !! index)))
                else Nothing

contains :: Eq k => k -> Map k v -> Int
contains k (Map map') = getValue (elemIndex k (fst (unzip map')))

getValue :: Num a => Maybe a -> a
getValue (Just a) = a
getValue Nothing = -1



put :: Eq k => (k, v) -> Map k v -> Map k v
put pair (Map map') = Map (put' pair map')


put' :: Eq key => (key, value) -> [(key, value)] -> [(key, value)]
put' pair @ (key, value) (x:xs)
    | length xs == 0 = [x,pair]
    | fst x == key = pair:xs
    | otherwise = x:(put' pair xs)