module Algos where

-- eco "abc" == "abbccc"

-- eco xs = concat [replicate i x | (i,x) <- zip [1..] xs]
-- eco xs = concat [replicate 1 "a" | (1,"a") <- zip [1..] "abc"]
-- eco xs = concat ["a" , replicate 2 "b" | (2,"b") <- zip [2..] "bc"]
-- eco xs = concat ["a" , "bb" replicate 3 "c" | (3,"c") <- zip [3..] "c"]
-- eco xs = concat ["a" , "bb", "ccc" | []]
-- eco xs = concat ["a" , "bb", "ccc"]
-- eco xs = "abbccc"
eco :: [a] -> [a]
eco xs = concat [replicate i x | (i,x) <- zip [1..] xs]