Programming Elixir ≥ 1.6

if and unless

In Elixir, if and its evil twin, unless, take two parameters: a condition and a keyword list, which can contain the keys do: and else:. If the condition is truthy, the if expression evaluates the code associated with the do: key; otherwise it evaluates the else: code. The else: branch may be absent.

iex> if 1 == 1, do: "true part", else: "false part"
"true part"

iex> if 1 == 2, do: "true part", else: "false part"
"false part"

Just as it does with function definitions, Elixir provides some syntactic sugar. You can write the first of the previous examples as follows:

iex> if 1 == 1 do
...>   "true part"
...> else
...>   "false part"
...> end
true part

unless is similar: ...