I managed to install asdf, then erlang and elixir via asdf.
I was able to create and test the example Mix project (page 19) successfully.
I’m confused where to put the very first example: one.ex with two functions (hello/0 and welcome/1). The filenames given start with elixir_examples/lib so I assumed that ‘lib’ is the same lib directory created on page 19, and thus created the one.ex file in a new examples/modules directory. However, running iex as shown on page 21 generates a “function Examples.Modules.One.hello/0 is undefined (module Examples.Modules.One is not available)” error message. I am invoking $ iex -S mix from the same directory that contains lib and mix.exs.
I’ve played around for a couple hours and am stumped. Thanks in advance for a hint!
Can you paste your file that contains defmodule Examples.Modules.One ? The module should be in lib, and the file name does not matter. The only thing that matters is you define the module and functions in a file that’s inside of lib.
BTW, all of the books code is available on the website at From Ruby to Elixir: Unleash the Full Potential of Functional Programming by Stephen Bussey (Search “Source Code”). I highly recommend this if you get really stuck on something, because it may be a really simple missed command or misunderstanding somewhere.
The primary cause was a typo in the “defmodule” in one.ex.
However, I still find the path to the example files confusing: just prior to setting up the examples, the book has us run “mix new examples” (p19) which creates a new folder, “examples,” which contains a “lib” folder where we are to place our source code. The first example on the following page, however, places the “one.ex” in a path that has those folder names in reverse: “elixir_examples/lib/examples/modules/one.ex” so it’s confusing, especially since the top-level directory is different than the “examples” directory just created, and then we have to add two empty directories inside lib (including a confusing second instance of “examples”.
I think I understand it now, but I found it a bit confusing. Enjoying working through the rest of the otherwise excellent book, though!
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Thank you Bruce.
You make fair points. The folder names in the example directory do not match yours exactly. This is a side effect of how I tried to keep Ruby and Elixir code obvious, but I probably should’ve made the paths match. (From the book bundler.)
It’s important to note that a file path inside of lib actually doesn’t matter. You could have one.ex at the top level and it would work. However, the most common pattern in the Elixir community is a subfolder for your project namespace, especially where each dot creates a new folder.
