Exercism.io Secret handshake exercise?

It’s fully open source.

Check out Exercism · GitHub

This is another one that is quite fun with binary pattern matching

defmodule Secret do
  def handshake(number) when is_integer(number) do
    handshake(<< number :: size(5) >>)
  end

  @code ["jump", "close your eyes", "double blink", "wink"]
  def handshake(<< reverse :: size(1), jump :: size(1), close :: size(1), double :: size(1), wink :: size(1) >>) do
    shake =
      [jump, close, double, wink]
      |> Enum.zip(@code)
      |> Enum.reduce([], fn
          {0, _}, acc -> acc
          {1, item}, acc -> [item | acc]
        end)

    # Since Enum.reduce/3 returns the list in reverse order,
    # we only reverse if the reverse bit is not set :-)
    if reverse == 1, do: shake, else: Enum.reverse(shake)
  end
end

iex> Secret.handshake 3
["wink", "double blink"]
hex> Secret.handshake 0b00111
["close your eyes", "double blink", "wink"]
iex> Secret.handshake 0b10111
["wink", "double blink", "close your eyes"]

So Exercism.io is a community driven effort ( by the Elixir community ? )
If so perhaps I could help as well? There is always strength in numbers.

The way the information is presented in the example makes no sense to me. “Recycling” the bits and pieces that are there leads me to this “best guess”:

iex(1)> import Bitwise
Bitwise
iex(2)> flags = 0b11011
27
iex(3)> check = 0b11010
26
iex(4)> (flags &&& check) == check # true - because all the necessary bits are set
true
iex(5)> flags = 0b11011
27
iex(6)> check = 0b10110
22
iex(7)> (flags &&& check) == check # false - because third bit is not set
false
iex(8)> 

Yes, we are on par with that. At least now after the relaunch. But as I said, there is a lot to do after the relaunch to identify exercises that do not suite the new product and community goals anymore. Even more work is to be done to rephrase them or to decide to remove them completely.

I hope I find some time later today, after the kids are in bed, to at least skim some exercises to find some examples of “pesky clients” and then draft a first issue that I can post on github to actually raise the attention of Katrina Owen to the problem and get some discussion around the topic started.

I also feel like that, but for the sake of learning the language I try to power through as much as possible.

@NobbZ Wonderful insight, however this is not Exercism.io’s purpose. It’s purpose is not to simulate pesky clients it is to give you objective exercises so you can learn the language.

@peerreynders So, this is confusing to me.
I fail to see how doing 0b11011 &&& 0b10110 which results in 18, is supposed to tell me that the 3rd bit is not set and how that affects the exercise.

If you are lucky and work for an employer that actually asks back… Congratulations. I’ve seen it differently a lot of times even though, I am in the lucky situation, that I’m developing on a core product that is mostly experimental, and as such requirements are discovered by myself and formalized by the team before they get implemented in future sprints.

Doesn’t even come close:

“We want this.”
“Why do you think you need that?”

… which sooner or later leads to the discovery that the actual problem needs a completely different solution.

Sometimes the assignments are purposely vague, it’s a bit in the spirit of the customer that only ever tells what he really needs a week after the deadline

But yes, I liked this under the old exercism, but the new should clean up with those. This exercises are scary and not in the warm and welcoming spirit the new exercism should have.

Those are the type of constraints that I like to see explicitly stated, otherwise more time is spent on trying to figure out what the intended problem is rather than solving the problem.

(I realize I’m in no position to complain given this is a volunteer effort - I just find the same to apply in other avenues.)