eFSA

eFSA.hs

eFSA :: (String, String, Int, Int) -> (String, String, Int, Int)
eFSA (source, lexeme, col, line)
    | nextChar == 'e' || nextChar == 'E' && isDigit secondChar
        = eFSA (tail source, nextChar : lexeme, col + 1, line)
    | isDigit nextChar
        = eFSA (tail source, nextChar : lexeme, col + 1, line)
    | otherwise (source, lexeme, col, line)
  where
    nextChar = head source
    secondChar = snd source