Problem 18

Extract a slice from a list.

Given a list, return the elements between (inclusively) two indices. Start counting the elements with 1. Indices outside of the list bounds (i.e. negative number, or beyond the length of the list) should be clipped to the bounds of the list.

Example

slice 3 7 (List.range 1 10) == (List.range 3 7) 
slice -7 -3 (List.range 1 10) == []

Unit test

import Array
import Html
import List

sublist : Int -> Int -> List a -> List a 
sublist start end list = 
    -- your implementation goes here
    []


main : Html.Html a 
main =
    Html.text
        <| case test of 
            0 -> 
                "Your implementation passed all tests."
            1 -> 
                "Your implementation failed one test."
            x -> 
                "Your implementation failed " ++ (toString x) ++ " tests."


test : Int
test =
    List.length <| List.filter ((==) False)
      [ True
      , sublist 3 7 (List.range 1 10) == List.range 3 7
      , sublist 2 100 [ 'a', 'b', 'c' ] == [ 'b', 'c' ]
      , sublist -1 2 (List.range 1 100) == [1, 2]
      , sublist -3 -2 [-3, -2, -1, 0, 1, 2, 3] == []
      , sublist 5 3 [ "indices", " are", "inverted"] == []
      , sublist 0 1 (List.range 1 10) == [1]
      , sublist -7 -3 (List.range 1 10) == []
      ]

Hint

1. Before you drop in the simplest solution, take a minute to consider the array of possibilities.

Solutions

Solutions