Instead of directly incorporating my simple spell checking code into my project, why not turn this into a library that I could more easily use in other places as well as share publicly.
I know that some other libraries exist but none appear to be a standard, and since I'm really doing this as an experiment forgive me for re-inventing the wheel a bit.
I'm following this official guide for creating a library.
Create a Project
Let's start with simply creating a new library.
$ mix new spell_chex
I prefer an evolutionary and iterative style of development so before I worry about the complexity of a GenServer
in my final spell checker build, I'll create the project with the naive implementation (discussed previously) and make sure I can create the library and then use the library in my host application.
Let's be good citizens and add some docs too:
defmodule SpellChex do
@moduledoc """
Module used to invoke SpellChex.
"""
@moduledoc since: "1.0.0"
@sample_words ["hello", "world", "elixir", "phoenix", "spell", "check", "dog", "cat"]
@doc """
Determines if a given `word` is in the list of known words.
Returns `true` or `false`.
## Examples
iex> SpellChex.exists?("dog")
true
iex> SpellChex.exists?("asdfas")
false
"""
@doc since: "1.3.0"
def exists?(word) do
# GenServer.call(__MODULE__, {:check_exists, word})
word in @sample_words
end
end
In order to get our docs to create we need at add the ex_doc
dependency to our mix.exs
.
defp deps do
[
{:ex_doc, "~> 0.31", only: :dev, runtime: false}
]
And let's test out those docs. (More on running docs locally here.)
mix deps.get
mix docs
cd doc
caddy file-server --browse --listen :5051
That should be it for the naive implementation. Now let's figure out how to build it locally and use it in our host project.
Consume the library locally
Eventually we will want to push our local code to github and publish on Hex, but why worry about publishing every time you want to test something out locally?
First thing to do is to update your host project to reference your new library with the path
option:
defp deps do
[
...
{:spell_chex, path: "../spell_chex"},
Grab your deps again (mix deps.get
) and now you can start using the library:
iex(1)> SpellChex.exists?("dog")
true
Configure the Library
Since the library relies on a GenServer
to create a dictionary of words we need to add our dictionary to the host application's start-up.
Update children
in lib/<host>/application.ex
:
def start(_type, _args) do
children = [
...
SpellChex.Dictionary,
...
]
Now you should be able to start your host mix app and test it out:
iex -S mix
...
iex(1)> SpellChex.exists?("dog")
true
iex(2)> SpellChex.exists?("blahblah")
false
iex(3)> SpellChex.exists?("bonsai")
true
Publish via Github
You could simply push your latest to main and then reference your library from the host app's mix.exs
like this
{:spell_chex, git: "https://github.com/byronsalty/spell_chex"},
But you may want to still utilize versioning. If so you'd tag in get like this:
git tag -a "0.0.1"
git push origin 0.0.1
# or
git push origin --tags
Then you can use the version in the mix.exs
:
{:spell_chex, git: "https://github.com/byronsalty/spell_chex", tag: "0.0.1"},
Publish to Hex
But maybe you want to make your library truly global...
Following this guide to publishing to Hex:
https://hex.pm/docs/publish
Highlights:
- Setup your hex account.
- Add all of the required metadata.
- Make sure your docs build.
- Publish!
mix hex.publish
Now you can use the standard mix.exs
dependency style:
{:spell_chex, "~> 0.0.1"},
Happy Coding!
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