CODEWITHSUNDEEP
elixirphoenix-framework
script
script

Reputation: 2167

Adding lists in a specific format

If I have a list like this: 

a = [1,2,3]

And second list like this: 

b = [4,5,6]

I want these lists to be added like this:

[1,2,3, some_atom:[4,5,6]]

So i want an atom to in the list like this.

I am trying this:

 a ++ [some_atom: b]

Its giving me the output:

[1, 2, 3 {:some_atom, [4, 5, 6]}]

Can any one suggest how can I do that if possible?

Thanks

Upvotes: 3

Views: 84

Answers (3)

ryanwinchester
ryanwinchester

Reputation: 12157

They are the same thing and work the same way. It is how Keyword lists work.

Try it in iex:

iex(1)> [foo: "bar"]
[foo: "bar"]

iex(2)> [{:foo, "bar"}]
[foo: "bar"]

Cool right?, Check it.

iex> [foo: "bar", baz: "bar"] == [{:foo, "bar"}, {:baz, "bar"}]
true

And your example:

iex> [1, 2, 3, some_atom: [4, 5, 6]] == [1, 2, 3, {:some_atom, [4, 5, 6]}]
true

iex

Upvotes: 1

Aetherus
Aetherus

Reputation: 8898

As long as you notice that [1,2,3, some_atom: [4,5,6]] is equivalent to [1,2,3, {:some_atom, [4,5,6]}], you should be able to figure out the answer yourself. And your original approach is correct. You can prove it by

a = [1,2,3]
b = [4,5,6]
c = a ++ [some_atom: b]

[1,2,3, some_atom:[4,5,6]] = c  # pattern matching passes

Upvotes: 1

Justin Wood
Justin Wood

Reputation: 10061

What you are getting is the proper result. In Elixir, a Keyword list is just a list of tuples. So,

[key: :value, other_key: :other_value]

is the same as

[{:key, :value}, {:other_key, :other_value}]

In fact, the first is just syntactic sugar for the second.

Upvotes: 1

Related Questions