Nested

A library to handle nested Elixir maps, a reimplementation of the Erlang nested library.

Requirements

Elixir 1.13 or newer

Building

git clone git@github.com:dgulinobw/nested_ex.git
cd nested_ex
mix
iex -S mix

Usage

Get

get the value of an existing key:

map = %{two: %{one: :target, one_side: 1}, two_side: 2}
Nested.get(map,[:two, :one])

:target

Or use a default in case the key does not exist:

map = %{two: %{one: :target, one_side: 1}, two_side: 2}
Nested.get(map,[:two, :some_unknown_key], :default)

:default

Put

Put some value under a key that might or might not exist:

map = %{two: %{one: :target, one_side: 1}, two_side: 2}
Nested.put(map, [:two, :one], :i_got_you)

%{two: %{one: :i_got_you, one_side: 1}, two_side: 2}

If there are more keys than in the original map, nested maps are created:

Nested.put(map, [:two, :down, :the, :rabbit, :hole], 42)

%{
  two: %{down: %{the: %{rabbit: %{hole: 42}}}, one: :target, one_side: 1},
  two_side: 2
}

Update

Replace an exiting value:

map = %{two: %{one: :target, one_side: 1}, two_side: 2}
Nested.update!(map, [:two, :one_side], 7)

%{two: %{one: :target, one_side: 7}, two_side: 2}

Instead of a value, you can pass a function with arity 1 which is passed the old value:

Nested.update!(map, [:two_side], fn(e) -> e*2 end)

%{two: %{one: :target, one_side: 1}, two_side: 4}

If you really mean to set the value to a fun you have to wrap it in an update fun:

Nested.update!(map, [:two_side], fn(_) -> fn(a, b) -> {a, b} end end)

%{
  two: %{one: :target, one_side: 1},
  two_side: #Function<41.125776118/2 in :erl_eval.expr/6>
}

Keys

List the keys in a map:

map = %{two: %{one: :target, one_side: 1}, two_side: 2}
Nested.keys(map, [:two])

[:one, :one_side]

Delete

Delete a key:

map = %{two: %{one: :target, one_side: 1}, two_side: 2}
Nested.delete(map, [:two, :one_side])

%{two: %{one: :target}, two_side: 2}

If the path does not exist, nothing changes:

map = %{two: %{one: :target, one_side: 1}, two_side: 2}
Nested.delete(map, [:two, :unknown, :path])

#{two => #{one => target,one_side => 1},two_side => 2}

TEST

mix test

TODO

Add the ability to pass functions to functions other than update!.