README.md

Exercise: Functions-5

Use the &... notation to rewrite the following.

Enum.map [1, 2, 3, 4], fn x -> x + 2 end
Enum.each [1, 2, 3, 4], fn x -> IO.inspect x end

Solution

There isn't much to this one. First, let's replace the fn x -> ... end with:

&(...)  

The function takes one parameter, which we can reference using &1, and then we just need to add 2 to it.

&(&1 + 2)

Plug that back in and we get:

Enum.map [1, 2, 3, 4], &(&1 + 2)

Let's do the same thing for the second line:

Enum.each [1, 2, 3, 4], &(IO.inspect &1)

And now, let's test it:

iex> Enum.map [1, 2, 3, 4], fn x -> x + 2 end  
[3, 4, 5, 6]  
iex> Enum.map [1, 2, 3, 4], &(&1 + 2)  
[3, 4, 5, 6]  

iex> Enum.each [1, 2, 3, 4], fn x -> IO.inspect x end  
1  
2  
3  
4  
:ok  
iex> Enum.each [1, 2, 3, 4], &(IO.inspect &1)  
1  
2  
3  
4  
:ok