What is `=INFO REPORT====` where is it coming from ? how to surpress it?

[NobbZ]

@sourcevault

mix compile takes way too long for coding

Unless you did something wrong, it should only recompile touched modules. But if you change a module that is used, included or required, you need to recompile all the modules that use it that way.

mix app.tree can help you to find out how compiletime dependencies.

[josevalim]

@sourcevault

mix compile takes way too long for coding - and we are talking about a bare app ! The only fast solution for Elixir (recompiling in Erlang or nodejs is not a problem since it happens in 1 second for a bare app)

I would be curious about what times you are seeing. mix compile --force in Ecto, which has 35k LOC over 68 files takes 5 seconds in my machine. And that is a full compilation. Elixir’s compiler is incremental so most times you are waiting considerably less.

@NobbZ

Unless you did something wrong, it should only recompile touched modules. But if you change a module that is use d, include d or require d, you need to recompile all the modules that use it that way.

Just to clarify: mix compile does all of it for you, you don’t have to track anything. mix compile should also be fast enough, if the concern is the experience (quitting the shell and restarting it), then you can use file system watchers or invoke recompile in the shell directly.

@NobbZ

mix app.tree can help you to find out how compiletime dependencies.

That is about dependencies between applications. mix xref graph is the one that is about modules but you are generally not supposed to care.

EDIT: the clarifications are not for you @NobbZ just expanding your comments.

[7stud]

@sourcevault

A few specific quirks (I hope you do not mind constructive criticism ) :

  use ExUnit.Case
  doctest KV

  test "greets the world" do
    assert KV.hello() == :world
  end

where is test , assert coming from ? is it being imported from ExUnit.Case

I’m new to Elixir as well, and I know some Erlang–but I also know Ruby pretty well, and I would describe Elixir as rubified Erlang, so Elixir has not been as difficult for me as Erlang was. Learning recursion in Erlang took a while.

In any case, I was very confused when I saw modules defined like this in Elixir:

defmodule My do
  import A
  require B
  use C

   ...
   ..
end

The only one of import, require, and use that I could understand was import, which allows you to use the unqualified names of the functions defined in A, e.g. do_stuff() v A.do_stuff(). In other words, import just affects the namespacing of names.

On the other hand, require and use employ black magic to inject function definitions (and other definitions) into the module where the require or use statement appears. The black magic is accomplished via an Elixir feature called macros, which is an advanced topic. I got so frustrated not understanding what the heck was going on when I saw use, require, and import lumped together, that I skipped straight away to the macros section of my book. If you want to gain some understanding of require and use then you need to learn about macros. In any case, that’s where test() and assert() come from.

Just yesterday, I was trying to figure out what doctest KV does. Well, doctest is a macro and you are passing it the argument KV, and the macro performs some black magic which allows you to do…something related to testing!

doctest is a macro that searches a specified module for code examples and automatically generates test cases.

See here.

[OvermindDL1]

@sourcevault

I am sorry but in Erlang you can specify a single entry point, here is a bare example :

That is for the interpreter runner, not when running in distribution mode. You can do the same with elixir.

[josevalim]

@7stud

On the other hand, require and use employ black magic to inject function definitions (and other definitions) i

There is no black magic in require. All require does is to allow you to invoke a macro in some module. But if you only do require Foo and nothing more, nothing should happen.

[7stud]

@josevalim

There is no black magic in require . All require does is to allow you to invoke a macro in some module. But if you only do require Foo and nothing more, nothing should happen.

Aargh! <mental model cracking> So, all macros are expanded at compile time whether or not they are require()'d anywhere?

Oh yeah, and this: require() insures that the module you are requiring gets loaded before the module containing the require statement.

[NobbZ]

@7stud

Aargh! <mental model cracking> So, all macros are expanded at compile time whether or not they are require()'d anywhere?

You can’t use a macro without having requireing or includeing the module that contains the macro.

[7stud]

@NobbZ

You can’t use a macro without having require ing or include ing the module that contains the macro.

I know that’s not true. Here’s proof:

defmodule My do
  defmacro go() do
    quote do
      def greet(), do: IO.puts "hello"
    end
  end
end

defmodule Test do
  require My
  My.go
end

Test.greet

Output:

~/elixir_programs$ iex macros2.ex

Erlang/OTP 20 [erts-9.3] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:10] [hipe] [kernel-poll:false]

hello

Interactive Elixir (1.6.6) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)>

No include required. Wait a minute…what the heck is include? I wrote include and I was thinking import.

[josevalim]

@7stud

Aargh! <mental model cracking> So, all macros are expanded at compile time whether or not they are require()'d anywhere?

You always have to require a module before you call a macro on it. That is require’s only purpose. In the example above, you used require. Note that import also requires it for you.

[7stud]

@josevalim

Note that import also require s it for you

I did NOT know that. Everything I’ve read says that you have to require macros…but import works as well. Thanks!

[NobbZ]

@7stud

You can’t use a macro without having require ing or include ing the module that contains the macro.

I know that’s not true. Here’s proof:

Yeah, by include I meant import. I tend to not use this one at all, I consider it polluting my namespace and I’m currently doing a lot of C, where we have #include preprocessor directive… Perhaps I was confused by that?

Still, in your “proof” of not needing to require or import modules, you used require, which I told you is a must have.