{- Remove Duplicates Function
   CSci 450/503, Fall 2016
   2016-11-26: H. Conrad Cunningham
-}

import Html exposing (..)

-- Function remdups takes a list of comparable values and returns the
-- list resulting from the removal of adjacent duplicates.  Type
-- variable comparable is restricted to values that can be compared.

remdups : List comparable -> List comparable
-- remdups : List Int -> List Int
remdups xs =
   case xs of
      x::y::ys ->
         if x == y then
            remdups (y :: ys)
         else
            x :: remdups (y :: ys)
      _        -> xs

-- Simple Display Functions

newline = br [] []

displayLines : List String -> List (Html msg)
displayLines ss = 
   case ss of
      []      -> []
      x :: xs -> text x :: newline :: displayLines xs

display : List String -> Html msg
display ls = p [] (displayLines ls)

-- Some testing

test1 = remdups []
test2 = remdups [1]
test3 = remdups [1,1]
test4 = remdups [1,2]
test5 = remdups [1,2,3]
test6 = remdups [1,2,2]
test7 = remdups [1,2,3,3,3]
test8 = remdups [1,1,1,2,3,3,3,3,4,5,5,5,5,6]

main =
  display 
     [ "remdups tests:"
     , toString test1
     , toString test2
     , toString test3
     , toString test4
     , toString test5
     , toString test6
     , toString test7
     , toString test8
     , "End!"
     ]