cool! could you show me how you defined &_?
what do you mean by monad’y composition?
cjen07
Eiji
@OvermindDL1: &_ is awesome idea! I also think about “update” pipe operator, but I have similar feeling like others about integer between | and >.
1
cjen07
OvermindDL1
I don’t, rather you overload the |> pipe operator and just override calls inside it that contain that. It is actually a pretty trivial to do transformation.
Like you know how the primary error handling in Erlang/Elixir are tagged tuples? Like you get :ok or {:ok, value} for a success result and a :error or {:error, reason} for a failure result and you have to pattern match on those with, say, case or so? Well that is a great pattern, and the BEAM as of OTP20 is even more optimized for these conditions, however it sucks if you want to, say, pipe the success value along but not the error conditions, like say this:
def safe_div(_n, 0), do: {:error, "Cannot divide by zero"}
def safe_div(n, d), do: {:ok, div(n, d)}
32
|> safe_div(4) # {:ok, 8}
|> safe_div(0) # {:error, "Cannot divide by zero"}
|> safe_div(2) # {:error, "Cannot divide by zero"}
|> map_error(16) # {:ok, 16}
|> return() # 16
And so forth or so. And it would still work with normal values, and would be overridable for all sorts of other things like success tuples, returning exceptions or so, etc…
The exceptional library already adds this ability to the pipe (optionally overridden, otherwise it also defines ~> by default).
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cjen07
OvermindDL1
PatNowak
I do admire that you wrote this library, but it looks certainly much harder to read that classic pipe operator 
0
benwilson512
Author of Craft GraphQL APIs in Elixir with Absinthe
def bar3() do
h =
1
|-2> foo(0, 0) = f # 3 = f
|-1> foo(0, 0) # 12
|> foo(0, 0) = g # 24 = g
|-1> foo(0, 0) # 96
|> foo(f, g) # 297
IO.inspect(h+1) # 298
:ok
end
I apologize for being such a downer, but this is completely indecipherable. How is this supposed to be an improvement over over the unwinded form?
f = foo(0, 0, 1)
f = foo(0, f, 0)
g = foo(f, 0, 0)
h = foo(g, f, g)
This seems to just prove all the concerns folks had about expanding on |>.
1
cjen07
Thanks for you reply, but I think your logic is wrong. If something is useless in one situation, you think it is useless in all situations.
I just gave the most complex/possible example to use. I never say that I will use foo function in real world.
I give you an example: infix/lib/infix/infix.ex at master · cjen07/infix · GitHub
in which file and {l0, l1} are temporary varaible, if you use this library, the pipe will not be broken into three parts.
By the way, metaprogramming/abstraction means less code but same functionality. Readability, I think, is not the only goal or even the goal in this process, similarly, I don’t think while(n < 10) cout << n++; increases any readability.
If the first time you learned the syntax &(&1), and you think it increases any readability than (fn x -> end) , I will apologize.
0