Optimize the inner Match or Conditional Case

For every conditional assignment, every time I need to write a new condition. for example-

    ready_for_eligible_account =
      cond do
        price_plan["standard_plan"]["monthly"] == 0 ->

        price_plan["standard_plan"]["monthly"] != 0 ->
    validation_msg = 
      case ready_for_eligible_account do
          true ->
            "Coupon Validated"
          false ->
            "Invalid Coupon"

How can I do the same in 1 conditional case? Also, tell the general way so that I could handle more than 2 conditional case. Your help will be appreciated.

This can be easily rewritten as a simple assignement:

ready = price_plan["standard_plan"]["monthly"] == 0

And this is easier to grasp when written as an if rather than a case:

message = if ready, do: "Coupon Validated", else: "Invalid Coupon"

Great. Thank you very much.

Your first expression whas of this kind:

result = cond do
  condition -> true
  not condition -> false

Which in its nature is very similar

result = if condition, do: true, else: false

Which can always be simplified to

result = condition

The second one is a bit different, but usually, whenever you have a case matching on true/false only, you usually can just replace it by an if, there might be cases where you want to explicitely true/false rather than truthy/falsey checks, then of course you need the case.

And to be honest, about any 2-clause-case that matches on an exact value rather than binding names, while the other arm uses _ can be rewritten into an if by just using Kernel.===/2 or Kernel.==/2, depending on the semantics you need.