module DNA (nucleotideCounts) where

import Data.Map (Map)

countLetters :: String -> Char -> Int
countLetters str c = length $ filter (== c) str

nucleotideCounts :: String -> Either String (Map Char Int)
nucleotideCounts xs = go xs []  where
    go [] acc = Right acc
    go (x:xs) acc = if x `elem` "ACGT" then ????  else Left "error"