7stud
I’m trying to use a require statement:
my_lib.exs:
defmodule MyLib do
require MyMath
def go(), do: MyMath.calc(1, 2)
end
Here’s the MyMath module:
my_math.exs:
defmodule MyMath do
def calc(x, y), do: x+y
end
Both files are in the same directory. Here is what I get:
~/elixir_programs$ iex my_lib.exs
Erlang/OTP 20 [erts-9.3] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:10] [hipe] [kernel-poll:false]
** (CompileError) my_lib.exs:2: module MyMath is not loaded and could not be found
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michalmuskala
Because macros can change semantics of the core language constructs, you have to explicitly opt-in into using them. This was a very early design decision.
mgwidmann
requiredoes not look for files at all, the module has to be already loaded in order for it to work in the way you are trying. If you add to the top of your fileCode.require_file("my_math.exs"), you should see it start working. If you do$ mix new my_projectand put these files inlib(as.exfiles not.exs) you won’t need to do anything and the compiler will find the right file automatically; this is the typical way to do things. After that, run$ iex -S mixand your code will be available for execution (type into the promptMyLib.go()).As for the code you’ve written, you don’t need a
requirestatement at all. Requires are for loading macros before they’re used, which your function is not (its just a plain function). You can remove therequire MyMathand everything will still work fine.You can read more about
alias,require,importandusehere: https://elixir-lang.org/getting-started/alias-require-and-import.htmlmgwidmann
Without a doubt you are causing yourself more headache than its worth. Create a new mix project and put the files in
liband call it a day. Mix makes this easy for this very reason.