Facing Problem while appending elements In a list

variable are immutable, you would need to use something like Enum.reduce.

def display(list) do
  list
  |> Combination.combine()
  |> Enum.reduce([], fn val, acc ->
    if Enum.sum(val) == 6 do
      [val | acc]
    else
      acc
    end
  end)
end

To display the list you could just pipe the result to IO.inspect

Combination.display([1,2,3,4]) |> IO.inspect()

I think this should give you what you want but looking at your combine, you might neet to reverse order some things.

I get the following output with your combine and my display:

iex> Combination.display([1,2,3,4,5])
[[3, 2, 1], [5, 1], [4, 2]]

Thanks a Lot Brother , i was stuct in this for last 3days

This is a typical code, just not for FP.
There is also a problem of scope, everything inside a do end block, will never make its way to the surrounding block.

I am facing another problem with the output
i.e this

when ever my
input is like - [1,2,3,4,5,6,7] , it gives me like this :-

erts@eyrc:~/fr_task0_9999/.vscode$ elixir practice.exs
[[4, 3, 2, 1], [7, 2, 1], [6, 3, 1], [5, 4, 1], [5, 3, 2], [7, 3], [6, 4]]
erts@eyrc:~/fr_task0_9999/.vscode$ 

And when i input something like this- [3, 5, 2, 7, 4, 2, 3] it gives me this :-

erts@eyrc:~/fr_task0_9999/.vscode$ elixir practice.exs
[
  [2, 5, 3],
  [2, 5, 3],
  [3, 2, 2, 3],
  [7, 3],
  [3, 4, 3],
  [3, 2, 5],
  [3, 2, 5],
  [3, 7]
]
erts@eyrc:~/fr_task0_9999/.vscode$ 

After puting several list i noticed that when ever my list is having repeating numbers like - [3, 5, 2, 7, 4, 2, 3] this

it shows like second one , but this not happens every time.

my code is this :

defmodule Combination do
  def combine([]) do
    []
  end
  def combine([head | tail]) do
    tail_combinations = combine(tail)
    merged_combinations = Enum.map(
      [[]] ++ tail_combinations,
      fn c -> c ++ [head] end
    )
    tail_combinations ++ merged_combinations
  end
  def display(list,v) do
    list
    |> Combination.combine()
    |> Enum.reduce([], fn val, acc ->
      if Enum.sum(val) == v do
        [val|acc]
      else
        acc
      end
    end)
    |>IO.inspect()
  end
end
Combination.display([3, 5, 2, 7, 4, 2, 3],10 )

I want the output in linear format like this - [[1,2], [3,4], [5,6]]

Maybe it would be easier if you could explain what your combine/1 is supposed to be doing. As in what do you expect the outcome to be when calling that function with a list of integers. We might be able to better help if we understand the reason for the function and not just the output

basically my combine/1 is creating subset of the given list
actually i have taken this code from internet
and yes i think the output of my combine is affecting the output of my display/1
this is what i get from my combine/1

Combination.combine([1,2,3,4])|>IO.inspect()

erts@eyrc:~/fr_task0_9999/.vscode$ elixir practice.exs
[
  [4],
  [3],
  [4, 3],
  [2],
  [4, 2],
  [3, 2],
  [4, 3, 2],
  [1],
  [4, 1],
  [3, 1],
  [4, 3, 1],
  [2, 1],
  [4, 2, 1],
  [3, 2, 1],
  [4, 3, 2, 1]
]

Combination.combine([1,2,3])|>IO.inspect()

erts@eyrc:~/fr_task0_9999/.vscode$ elixir practice.exs
[[3], [2], [3, 2], [1], [3, 1], [2, 1], [3, 2, 1]]
erts@eyrc:~/fr_task0_9999/.vscode$ 

So can u tell me why this is happening ??

Are you maybe looking for something like Enum.chunk_every/2?

iex> Enum.chunk_every([1, 2, 3, 4, 5, 6], 2)
[[1, 2], [3, 4], [5, 6]]

You’re saying display the subsets with a sum of 10, but the sums you’re outputting is 3, 5, 15?

This is another question related to this

https://forum.elixirforum.com/t/beginner-needs-help-with-sum-of-subsets/50511/78

I was just giving u the example of output format