Can I concatenate strings in Elixir and use the pipe operator?
Yes, you can, by passing the full path to the function, which in this case is Kernel.<>: iex(1)> “foo” |> Kernel.<>(“bar”) “foobar”
elixir
Many to Many relationship in Ecto
This is an old question and the previously accepted answer was no longer the de facto way. Ecto now supports HABTM or many to many associations. https://hexdocs.pm/ecto/Ecto.Schema.html#many_to_many/3 many_to_many :users, MyApp.User, join_through: “chat_group_users”
using a package locally with hex.pm
Yes it is. In your mix.exs, you can list the dependency with the :path keyword (very similarly to what you do with gems). def dependencies do [{:testing_dep, path: “/Users/me/testing_dep”}] end You can read a list of all the supported options (e.g., pulling the dependency from GitHub or from a Git repository) in the documentation for … Read more
Loop through a Map’s key-value pairs
Turns out you iterate over a Map exactly like you do over a Keyword List (i.e. you use a tuple): Enum.each(%{a: 1, b: 2, c: 3}, fn {k, v} -> IO.puts(“#{k} –> #{v}”) end) Comprehensions also work: for {k, v} <- %{a: 1, b: 2, c: 3} do IO.puts(“#{k} –> #{v}”) end Note: If you … Read more
Count the Number of Entries in an Ecto Repository
The options that Dogbert has provided are both correct and should be used for Ecto 1.x. In Ecto 2.0 you can use Repo.aggregate/4 Repo.aggregate(Post, :count, :id)
Installing dependencies in Elixir
If you are looking for something similar to npm install –save, then this does not exist in Elixir. You install things by adding them to deps: in the mix.exs file in your project then running mix deps.get. The other way you may wish to install certain applications is via a mix archive allowing this mix … Read more
Elixir Remove Duplicates From List
Enum.uniq does what you want, for example: iex(6)> Enum.uniq([1,26,3,40,5,6,6,7]) [1, 26, 3, 40, 5, 6, 7] In terms of how you’d implement it you could write a recursive function like so: defmodule Test do def uniq(list) do uniq(list, MapSet.new) end defp uniq([x | rest], found) do if MapSet.member?(found, x) do uniq(rest, found) else [x | … Read more
How can pattern matching be done on text?
defmodule MatchStick do def doMatch(“a” <> rest) do 1 end def doMatch(_) do 0 end end You need to use the string concatenation operator seen here Example: iex> “he” <> rest = “hello” “hello” iex> rest “llo”
What does “|>” mean in elixir?
This is the pipe operator. From the linked docs: This operator introduces the expression on the left-hand side as the first argument to the function call on the right-hand side. Examples iex> [1, [2], 3] |> List.flatten() [1, 2, 3] The example above is the same as calling List.flatten([1, [2], 3]).
How to check if a string is blank in Elixir
String.trim/1 seems to do the trick as of Elixir 1.3.0. strip still works, but it was soft deprecated in the 1.3.0 release and it isn’t listed in the String docs.