elixir

问题 I've noticed something surprising with Elixir's for comprehensions when used to pipe the results into a function. For example, these forms work: foo = fn(list) -> for n <- list do n + 1 end |> Enum.reverse end foo.([1,2,3]) # [4, 3, 2] foo = fn(list) -> for(n <- list, do: (n + 1)) |> Enum.reverse end foo.([1,2,3]) # [4, 3, 2] But this doesn't, as it considers the |> Mod.func on the second line part of the do block of the macro: foo = fn(list) -> for n <- list, do: n + 1 |> Enum.reverse end

问题 Well, I am looking for a good way to pass multiple elements (same column name) that I've retrieved from db into the channels payload. For example: ppl = Repo.all(People) will return two results with id: 1, name: Mike , id: 2, name: John . The name: (column name) is used for both Mike and John, but when passing through channels payload, I can only pass one map, where can't have both name: John, name: Mike at the same time. As I understood channels, we use a map(payload) that is send back to

问题 I have following statement iex(5)> a = <<3>> <<3>> iex(6)> b = <<a::binary>> <<3>> First line, I created a binary with value 3. On third line I want that the shell shows me 00000011 not 3. I know it does not make sense first the create a binary(1.line) then convert to binary again. But I was expecting that shell shows me 00000011 instead of 3. When binary as float like iex(7)> a = << 5.3 :: float >> <<64, 21, 51, 51, 51, 51, 51, 51>> I do not understand, why it shows me this numbers? 回答1:

问题 I'm trying to find a list a configurable options for mix format to put in the formatter config file, but I can't for the life of me find it. It's not in the mix format docs or anywhere else I've looked. Anyone know where I can find this information? 回答1: It turns out that mix format does not have a lot of options to set, and what you see on the mix docs page is exactly what you get. It seems there are not a breadth of settings to make it more opinionated. 回答2: You should read the docs:

问题 Using Elixir V1.1.1 on OS X I am having problems getting my head around the Elixir function definition syntax. Given a function definition: def foobar(arg1, arg2), do: <<something>> end It seems that in some cases the comma after the parenthesis is required, other times it is not. Likewise the colon after the 'do' and likewise the closing 'end'. I am sure I am vastly over-complicating the situation, but this seems like a weird setup for a programming language. Under what circumstances are

问题 I'm trying to setup an instance on my phoenix app. I'm actually able to generate the app but I'm getting an error when trying to connect to the DB: ERROR: 21:11:31.017 [error] Postgrex.Protocol (#PID<0.2223.0>) failed to connect: ** (DBConnection.ConnectionError) tcp connect (/tmp/cloudsql/statcasters:us-central1:statcastersdb): no such file or directory - :enoent I'm not sure what is wrong? The file seems to exist but it seems to say it doesn't: prod.secret.exs: config :statcasters,

问题 This question already has answers here : Elixir lists interpreted as char lists (2 answers) Closed last year . I have the following input: [ [ {"title", "Aaaaaaaaa aaaaaaaaaaa aa aaa oaaaaaaaa"}, {"title", "Aaaaaaa aa aaaa aaa.aa"}, {"title", "Aaaaaaaaaaaa Aaaaaaa, aaa Aaaaaaa"}, {"title", "Aaaa Aaaaaaaa aaaa Aaaaa"}, {"title", "Aaaaaaa Aaaaaaa aaaa Aaaaa"}, {"title", "Aaaaa Aaaaaaa aa Aaaaaa"}, {"title", "Aaaaaaaaa Aaaaa Aaaa Aaaaaaa, Aaa Aaaaaaa"}, {"title", "Aaaaaaaaa Aaaaaaa Aaaaaa

问题 This question already has answers here : Elixir lists interpreted as char lists (2 answers) Closed last year . I have the following input: [ [ {"title", "Aaaaaaaaa aaaaaaaaaaa aa aaa oaaaaaaaa"}, {"title", "Aaaaaaa aa aaaa aaa.aa"}, {"title", "Aaaaaaaaaaaa Aaaaaaa, aaa Aaaaaaa"}, {"title", "Aaaa Aaaaaaaa aaaa Aaaaa"}, {"title", "Aaaaaaa Aaaaaaa aaaa Aaaaa"}, {"title", "Aaaaa Aaaaaaa aa Aaaaaa"}, {"title", "Aaaaaaaaa Aaaaa Aaaa Aaaaaaa, Aaa Aaaaaaa"}, {"title", "Aaaaaaaaa Aaaaaaa Aaaaaa

问题 I need to perform some actions when the user leaves a channel (in most cases where they close the tab voluntarily, but there may also be a connection loss/timeout etc.) According to posts like https://elixirforum.com/t/phoenix-presence-run-some-code-when-user-leaves-the-channel/17739 and How to detect if a user left a Phoenix channel due to a network disconnect?, intercepting the "presence_diff" event from Presence seems to be a foolproof way to go, as it should also covers the cases where

问题 I'm tying to make an API where an anonymous function are composed from macros, e.g. transform [x, y], do: x + y transform x, do: x should use the transform head and body[:do] as the heads and bodies for an anonymous function. For example, the above macro calls The example above should be collected into: fn [x, y] -> x + y; x -> x end With unquote fragments it's easy to create new named function def s, but not new anonymous functions: iex> val = 1 iex> fn() -> unquote(val) end ** (CompileError