Wouldn't this suffice?
```
defguard is_real_map(x) when is_map(x) and not is_struct(x)
```
On Tue, Jan 03, 2023 at 11:34 PM, Andrey Yugai < andr...@pm.me > wrote:
>
> There's also an option of pattern matching any struct, not exactly a
> guard, but changing your code a bit shouldn't be a problem
>
>
> ```
>
>
> def foo(%_{} = _struct), do...
>
>
> def foo(map) when is_map(map), do...
>
>
> ```
>
>
>
>
>
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> Sent from Proton Mail mobile
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> -------- Original Message --------
> On 4 Jan 2023, 04:03, Jay Rogov < rogovyaroslav@ gmail. com (
> rogovyaros...@gmail.com ) > wrote:
>>
>> Also note that there's is_map_key/2 guard that serves the same purpose
>> when used as `is_map_key(arg, :__struct__)`, allowing only maps but not
>> structures:
>> https:/ / hexdocs. pm/ elixir/ 1. 14. 2/ Kernel. html#is_map_key/ 2 (
>> https://hexdocs.pm/elixir/1.14.2/Kernel.html#is_map_key/2 )
>>
>> On Thursday, 22 December 2022 at 4:22:30 pm UTC+1 halos...@gmail.com
>> wrote:
>>
>>
>>> I think that this is an interesting idea, but as Enumerable is a protocol,
>>> it is possible to implement enumerability for any given struct, as
>>> `MapSet` is enumerable.
>>>
>>>
>>> This SO answer (
>>> https://stackoverflow.com/questions/39609255/how-can-i-check-whether-the-protocol-is-implemented#39609295
>>> ) suggests using the Protocol. impl_for/ 1 ( http://Protocol.impl_for/1 )
>>> callback
>>> instead. It can’t be used as a guard, but it gives a more accurate answer.
>>>
>>>
>>>
>>> Whether `is_real_map/1` (or a different name) is more readable than `when
>>> is_map(term) and not is_struct(term)`, I can’t say because if I need to
>>> handle structs differently, I would generally use two different function
>>> heads (`def foo(term) when is_struct(term) do term |> Map.from_struct() |>
>>> foo() end` and `def foo(term) when is_map(term) do … end`).
>>>
>>>
>>> -a
>>>
>>>
>>> On Thu, Dec 22, 2022 at 1:25 AM vtm < vtmil... @ gmail. com > wrote:
>>>
>>>
>>>> hey all, thanks for you work on such a beautiful lang.
>>>>
>>>>
>>>> Small proposal. People sometimes get confused about data structures which
>>>> based on maps.
>>>> for instance:
>>>> ```
>>>> iex(3)> {:ok, datetime} = DateTime. now ( http://datetime.now/ )
>>>> ("Etc/UTC")
>>>>
>>>> {:ok, ~U[2022-12-22 05:53:36.228720Z]}
>>>> iex(5)> is_struct(datetime)
>>>> true
>>>> iex(6)> is_map(datetime)
>>>>
>>>> true
>>>> ```
>>>> but here i got an error
>>>> ```elixir
>>>> iex(11)> Enum.each(datetime, &Function.identity/1)
>>>> ** (Protocol.UndefinedError) protocol Enumerable not implemented for
>>>> ~U[2022-12-22 05:53:36.228720Z] of type DateTime (a struct)
>>>>
>>>> ```
>>>>
>>>>
>>>> i have in a codebase in function definition something like
>>>> `where is_map(map_name) and not is_struct(map_name)`
>>>> what i suggest to do is to create a macro `is_real_map` to check only real
>>>> maps as a key-value storage with Enumerable impl
>>>> ```elixir
>>>> @doc """
>>>> Returns true if `term` is a map and not is struct; otherwise returns
>>>> `false`.
>>>>
>>>> Allowed in guard tests.
>>>>
>>>> ## Examples
>>>>
>>>> iex> is_real_map(%{oi: :blz})
>>>> true
>>>>
>>>> iex> is_real_map(URI.parse("/"))
>>>> false
>>>>
>>>> """
>>>> @doc since: "1.16.0", guard: true
>>>> defmacro is_real_map(term) do
>>>> case __CALLER__.context do
>>>> nil ->
>>>> quote do
>>>> case unquote(term) do
>>>> %_{} -> false
>>>> %{} -> true
>>>> _ -> false
>>>> end
>>>> end
>>>>
>>>> :match ->
>>>> invalid_match!(:is_real_map)
>>>>
>>>> :guard ->
>>>> quote do
>>>> is_map(unquote(term)) and not :erlang.is_map_key(:__struct__,
>>>> unquote(term))
>>>> end
>>>> end
>>>> end
>>>>
>>>> ```
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>> --
>>>> You received this message because you are subscribed to the Google Groups
>>>> "elixir-lang-core" group.
>>>> To unsubscribe from this group and stop receiving emails from it, send an
>>>> email to elixir-lang-co... @ googlegroups. com.
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>>>> msgid/ elixir-lang-core/
>>>> 1f26dae3-9c67-446b-91d0-51bf1c5f3666n%40googlegroups.
>>>> com (
>>>> https://groups.google.com/d/msgid/elixir-lang-core/1f26dae3-9c67-446b-91d0-51bf1c5f3666n%40googlegroups.com?utm_medium=email&utm_source=footer
>>>> ).
>>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>> Austin Ziegler • halos... @ gmail. com • aus... @ halostatue. ca
>>> http:/ / www. halostatue. ca/ ( http://www.halostatue.ca/ ) • http:/ /
>>> twitter.
>>> com/ halostatue ( http://twitter.com/halostatue )
>>>
>>
>>
>>
>>
>>
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>>
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>> me (
>> https://groups.google.com/d/msgid/elixir-lang-core/gCO3cNmTH8s-grC61yt_KsSqoJ5CCZzYiPqA5X0S3Q1ZgoZ8j7usrix2xMFr-iGAdSl5X_N1NM-mvniP4KoOnkD1bRsrmtMoln_80Jk4v4A%3D%40pm.me?utm_medium=email&utm_source=footer
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