Feedback on Erlang Lists processing function

Question

I have just started learning erlang...I am just practicing the recursion and all in erlang...I tried to write a few of the list processing functions on my own in erlang...Can someone review the code and give some advice on it...

-module(listma).
-export([duplicates/1,reverse/1])
%% Remove the duplicates in a list
duplicates(List) ->
 duplicates(List,[]).
duplicates([Head|Tail],Newlist) ->
 Insert = 
 fun(H,N) -> 
 case [H] -- N of
 [] -> N;
 [H] -> [H|N]
 end
 end,
 duplicates(Tail,Insert(Head,Newlist));
duplicates([],Outputlist) ->
 reverse(Outputlist).
%% Reverse a list
reverse(List) ->
 reverse(List,[]).
reverse([Head|Tail],Newlist) ->
 reverse(Tail,[Head|Newlist]);
reverse([],Outputlist) ->
 Outputlist.

Answer 1

Your Insert lambda doesn't use any context so you could rewrite it as a top-level function or move its body to the clause. And you could use lists:member/2 instead of --.

I'd write first clause like this:

duplicates([Head | Tail], Acc) ->
 NewAcc = case lists:member(Head, Acc) of
 true ->
 Acc;
 _ ->
 [Head | Acc]
 end,
 duplicates(Tail, NewAcc);

• user23980: Thanks for the feedback Dmitry...Thank you so much...The Insert Lambda is useless here as you said...I will remove it...I wanted to practice lists processing functions without the use of lists Built in functions like member,delete,append,etc..Thats why i ignored lists:member thing and used -- operator....Thanks again Dmitry...Thank you so much
• Dmitry Belyaev: Well, you can write your own member function too without use of -- =)