In the previous chapter, we saw Elixir provides
/ as arithmetic operators, plus the functions
rem/2 for integer division and remainder.
Elixir also provides
-- to manipulate lists:
iex> [1, 2, 3] ++ [4, 5, 6] [1, 2, 3, 4, 5, 6] iex> [1, 2, 3] --  [1, 3]
String concatenation is done with
iex> "foo" <> "bar" "foobar"
Elixir also provides three boolean operators:
not. These operators are strict in the sense that they expect a boolean (
false) as their first argument:
iex> true and true true iex> false or is_atom(:example) true
Providing a non-boolean will raise an exception:
iex> 1 and true ** (BadBooleanError) expected a boolean on left-side of "and", got: 1
and are short-circuit operators. They only execute the right side if the left side is not enough to determine the result:
iex> false and raise("This error will never be raised") false iex> true or raise("This error will never be raised") true
Note: If you are an Erlang developer,
orin Elixir actually map to the
orelseoperators in Erlang.
Besides these boolean operators, Elixir also provides
! which accept arguments of any type. For these operators, all values except
nil will evaluate to true:
# or iex> 1 || true 1 iex> false || 11 11 # and iex> nil && 13 nil iex> true && 17 17 # ! iex> !true false iex> !1 false iex> !nil true
As a rule of thumb, use
not when you are expecting booleans. If any of the arguments are non-boolean, use
Elixir also provides
> as comparison operators:
iex> 1 == 1 true iex> 1 != 2 true iex> 1 < 2 true
The difference between
=== is that the latter is more strict when comparing integers and floats:
iex> 1 == 1.0 true iex> 1 === 1.0 false
In Elixir, we can compare two different data types:
iex> 1 < :atom true
The reason we can compare different data types is pragmatism. Sorting algorithms don’t need to worry about different data types in order to sort. The overall sorting order is defined below:
number < atom < reference < function < port < pid < tuple < map < list < bitstring
You don’t actually need to memorize this ordering, it’s enough to know that this ordering exists.
For reference information about operators (and ordering), check the reference page on operators.
In the next chapter, we are going to discuss pattern matching through the use of
=, the match operator.
© 2012 Plataformatec
Licensed under the Apache License, Version 2.0.