Fix compile-time warnings for Elixir 1.19.1

[dimamik]

Fixes all compile-time warnings for Elixir 1.19.1:

==> axon
Compiling 27 files (.ex)
     warning: incompatible types given to Kernel.apply/2:

         apply(Axon.Initializers, [])

     given types:

         Axon.Initializers, empty_list()

     but expected one of:

         fun(), list(term())

     typing violation found at:
     │
 135 │                 apply(Axon.Initializers, [])
     │                 ~
     │
     └─ lib/axon/quantization.ex:135:17: Axon.Quantization.weight_only_quantized_dense/3

    warning: Tuple.append/2 is deprecated. Use insert_at instead
    │
 49 │     Nx.reshape(scales, Tuple.append(ones, :auto))
    │                              ~
    │
    └─ lib/axon/quantization/layers.ex:49:30: Axon.Quantization.Layers.reshape_scales/2
    └─ lib/axon/quantization/layers.ex:54:23: Axon.Quantization.Layers.reshape_output/2

    warning: got "@impl true" for function __stream__/7 but no behaviour specifies such callback. The known callbacks are:

      * Nx.Defn.Compiler.__compile__/4 (function)
      * Nx.Defn.Compiler.__jit__/5 (function)
      * Nx.Defn.Compiler.__partitions_options__/1 (function)
      * Nx.Defn.Compiler.__to_backend__/1 (function)

    │
 18 │   def __stream__(_, _, _, _, _, _, _), do: raise("not implemented")
    │   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    │
    └─ lib/axon/defn.ex:18: Axon.Defn (module)

      warning: a struct for Axon.Loop.State is expected on struct update:

          %Axon.Loop.State{
            state
            | epoch: epoch + 1,
              metrics: zero_metrics,
              iteration: 0,
              max_iteration: state.max_iteration
          }

      but got type:

          dynamic()

      where "state" was given the type:

          # type: dynamic()
          # from: lib/axon/loop.ex
          {:continue, state}

      when defining the variable "state", you must also pattern match on "%Axon.Loop.State{}".

      hint: given pattern matching is enough to catch typing errors, you may optionally convert the struct update into a map update. For example, instead of:

          user = some_function()
          %User{user | name: "John Doe"}

      it is enough to write:

          %User{} = user = some_function()
          %{user | name: "John Doe"}

      typing violation found at:
      │
 1695 │ ...                   %State{
      │                       ~
      │
      └─ lib/axon/loop.ex:1695:29: Axon.Loop.run/4

      warning: a struct for Axon.Loop.State is expected on struct update:

          %Axon.Loop.State{state | epoch: epoch + 1, iteration: 0}

      but got type:

          dynamic(%{..., epoch: term(), metrics: term()})

      where "state" was given the type:

          # type: dynamic(%{..., epoch: term(), metrics: term()})
          # from: lib/axon/loop.ex
          {:halt_epoch, %{epoch: epoch, metrics: metrics} = state}

      when defining the variable "state", you must also pattern match on "%Axon.Loop.State{}".

      hint: given pattern matching is enough to catch typing errors, you may optionally convert the struct update into a map update. For example, instead of:

          user = some_function()
          %User{user | name: "John Doe"}

      it is enough to write:

          %User{} = user = some_function()
          %{user | name: "John Doe"}

      typing violation found at:
      │
 1927 │         {:cont, {batch_fn, final_metrics_map, %State{state | epoch: epoch + 1, iteration: 0}}}
      │                                               ~
      │
      └─ lib/axon/loop.ex:1927:47: Axon.Loop.halt_epoch/5

Generated axon app

[josevalim]

Woot, it found an actual bug :)

[polvalente]

I this change correct for < 1.19?

[dimamik]

I'm not sure honestly, isn't this local-only thing and just a pure function otherwise? I thought it won't break even if not supported

[josevalim]

We suport this for a few versions already and yes, it won't break users.

[dimamik]

@josevalim

Woot, it found an actual bug :)

Can you elaborate more? The code seems legit...

[josevalim]

@dimamik I meant this warning is an actual bug:

     warning: incompatible types given to Kernel.apply/2:

         apply(Axon.Initializers, [])

     given types:

         Axon.Initializers, empty_list()

     but expected one of:

         fun(), list(term())

     typing violation found at:
     │
 135 │                 apply(Axon.Initializers, [])
     │                 ~
     │
     └─ lib/axon/quantization.ex:135:17: Axon.Quantization.weight_only_quantized_dense/3

It needs to be fixed. :)