Validates that a value is not a member of a given collection using an Eq comparator.

NotIn enforces an exclusion constraint of the form: “value must not be one of these”.

Membership is defined by an Eq instance, not by structural equality or Elixir’s in operator.

Options

• :values (required) The list of disallowed values.

• :eq (optional) An equality comparator. Defaults to Funx.Eq.Protocol.

• :message (optional) A custom error message callback (value -> String.t()) used to override the default error message on failure.

Semantics

• If the value matches any element in :values under Eq, validation fails.
• If the value does not match any element, validation succeeds.
• Nothing values are preserved and treated as not applicable.
• Just values are unwrapped before comparison.

Examples

iex> Funx.Validator.NotIn.validate("deleted", values: ["active", "inactive"]) %Funx.Monad.Either.Right{right: "deleted"}

iex> Funx.Validator.NotIn.validate("active", values: ["active", "inactive"]) %Funx.Monad.Either.Left{

left: %Funx.Errors.ValidationError{
  errors: ["must not be one of: [\"active\", \"inactive\"]"]
}

}

iex> Funx.Validator.NotIn.validate(%Funx.Monad.Maybe.Nothing{}, values: ["a", "b"]) %Funx.Monad.Either.Right{right: %Funx.Monad.Maybe.Nothing{}}