[erlang-questions] create list quesion

Kyle Neal kyle@REDACTED
Tue Jan 27 16:07:42 CET 2015

I think we need a little more clarification...

On Tue, Jan 27, 2015 at 9:15 AM, Roelof Wobben <r.wobben@REDACTED> wrote:

> Hello,
> I try now to solve a challenge where I must make a list  from a range,
> So for example if I do create(2) the outcome have to be [ 1, 2]

Here you are saying create(N) should create a list from 1-N.

> So i can do
> create(0) ->
>   print array
> but as far as I know the list is then not in the scope so I cannot use it
> when I do
> create(2) ->
>   add the 2 to the array.

Here you are saying create(2) should ONLY add 2 to the list, when
previously you said create(2) should create a list from 1-2. Now, if you
are saying that create(N) should create a list from 1-N OR list:last()-N
(meaning it should be in range), then you would first have to check if N is
in the current list. If not, create the list, if so cancel

EX) (Using my assumption)

create(0) ->
         print array.

create(N) ->
          case lists:member(N, list) of
                     true ->
                      false ->
                              get last element of list (L),
                              append L-N to current list (L can also be
nothing, if this is the first call to this function in which case it should
append 1-N)

This should always work because the function is generating a list from A-B.
And you can using something like ets with ordered_set or something similar
to keep it in order.
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