@callback can_return_nil?(func :: map()) :: boolean()

Whether or not the operator can evaluate to nil.

@callback evaluate(term()) :: term()

Evaluates the operator in Elixir

@callback evaluate_nil_inputs?() :: boolean()

If true, will be allowed to evaluate nil inputs.

If false (the default), any nil inputs will cause a nil return.

@callback new(term(), term()) ::
  {:ok, term(), term()} | {:ok, term()} | {:known, boolean()} | {:error, term()}

Create a new predicate. There are various return types possible:

• {:ok, left, right} - Return the left/right values of the operator
• {:ok, operator} - Return the operator itself, this or the one above are acceptable
• {:known, boolean} - If the value is already known, e.g 1 == 1
• {:error, error} - If there was an error creating the operator

@callback returns() :: [
  :any | :same | Ash.Type.t() | {Ash.Type.t(), constraints :: Keyword.t()}
]

The types that the expression can return. Should be one entry in the list for each entry in types.

@callback to_string(
  struct(),
  Inspect.Opts.t()
) :: term()

The implementation of the inspect protocol.

If not defined, it will be inferred

@callback types() :: [
  :any | :same | [Ash.Type.t() | {Ash.Type.t(), constraints :: Keyword.t()}]
]

The types accepted by the operator. Defaults to [:same, :any], which is any values of the same type.