I have prepared small example of macro that does this already:
defmodule F do
defmacro pipe_to(pipe, {function, _env, args}) when is_atom(function) and
is_list(args) do
func_arg = quote do: a
args =
for arg <- args do
case arg do
{:_, _, _} -> func_arg
_ -> arg
end
end
quote do
(fn unquote(func_arg) -> unquote(function)(unquote_splicing(args))
end).(unquote(pipe))
end
end
end
It is not perfect yet, as for example this do not allow `Mod.func()` calls,
but is is working pretty well as is.
W dniu wtorek, 13 sierpnia 2019 17:42:17 UTC+2 użytkownik OvermindDL1
napisał:
>
> On Tuesday, August 13, 2019 at 3:04:03 AM UTC-6, José Valim wrote:
>>
>> I really want to avoid new syntactical constructs or special casing
>> anonymous functions as I believe it will be more confusing in the long term.
>>
>
> At that point adding in `.()` isn't a big deal, that's why it's pretty
> well fine as it is honestly for those kind of things.
>
> The main issue is just piping into another 'argument' of a function call,
> like the erlang standard library very much expects the 'subject' to be at
> the end, so I end up having to do a lot of things like:
> ```
> args
> |> transform_them()
> |> (&send(pid, &1)).()
> ```
> When it would look and feel so much more clean via anything like:
> ```
> args
> |> transform_them()
> |> &send(pid, &1) # Special case when `&` is in first position, though
> that does run into the expecting passing a `fun` to work
>
> args
> |> transform_them()
> |> send(pid, _) # Pipe into the 'hole'
>
> args
> |> transform_them()
> |> send(pid, _1) # Maybe index it, though this seems entirely needless
>
> args
> |> transform_them()
> |> send(pid, &0) # Or use `&0` as a pipe value, though then it looks less
> like an obvious hole and thus more easy to 'scan' past
>
> args
> |> transform_them()
> ~> send(pid, _) # Perhaps a different pipe operator for piping into, but
> this seems needless when `|>` can do it just fine
> ```
>
> All of which are much more easily read. And there are libraries for doing
> just this, they 'feel' so much more clean when I use them. With all of all
> of the above no closures even need to be created, it doesn't look like an
> anonymous function (except maybe the `&0` one), the prior value is just
> dumped into 'that' slot instead of the front slot. Honestly I'd prefer if
> it always required `_`, no magic 'stuff into front position' or anything,
> this would even allow you to reference the value more than once (set it to
> a gensym'd name then and put that in the holes).
>
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