Potential solution to question 3 from SDG student interview

SdgStringSolver.hs

module SdgStringSolver where

import Data.List
import Data.Char

help = "Run findTargetSubString against a test case such as test1 or test2."

target = "sdg"

test1 = ["SDGxx", "xxSDG", "xSDGx"] -- All results are true
test2 = ["SxDG", "S", "xxSD"] -- All results are false

findTargetSubString [] = []
findTargetSubString a = zip (map (\s -> elem target (breakString s 3)) a) a

breakString :: String -> Int -> [String]
breakString [] _ = []
breakString (a:as) n
  | n < 1 = []
  | otherwise = take n (map toLower (a:as)) : breakString as n

----- Or if you're more familiar with Data.List and you like one-liners: -----

alsoFindTargetSubstring a = zip (map (isInfixOf target . map toLower) a) a

Even cleaner if you add one more custom function:

zipMap fn a = zip (map fn a) a