introduction.md

Anonymous Functions

Functions are treated as first class citizens in Elixir. This means functions:

• Named and anonymous functions can be assigned to variables.
• Named and anonymous functions can be passed around like data as arguments and return values.
• Anonymous functions can be created dynamically.

Anonymous functions, in contrast to named functions, don't have a static reference available to them, they are only available if they are assigned to a variable or immediately invoked.

We might use anonymous functions to:

• Hide data using lexical scope (also known as a closure).
• Dynamically create functions at run-time.

Anonymous function start with the reserved word fn, the arguments are separated from the body of the function with the -> token, and they are finished with an end. As with named functions, the last expression in the function is implicitly returned to the calling function.

To invoke a function reference, you must use a . between the reference variable and the list of arguments:

function_variable = fn param ->
  param + 1
end

function_variable.(1)
# => 2

You can even use short hand capture notation to make this more concise:

variable = &(&1 + 1)

variable.(1)
# => 2

Closures

Anonymous functions in Elixir are closures. They can access variables that are in scope when the function is defined.

a = 7
square = fn -> a * a end
square.()
# => 49

Bit Manipulation

Elixir supports many functions for working with bits found in the Bitwise module.

• &&&/2: bitwise AND
• <<</2: bitwise SHIFT LEFT
• >>>/2: bitwise SHIFT RIGHT
• ^^^/2: bitwise XOR
• |||/2: bitwise OR
• ~~~/1: bitwise NOT

Here is an example how to use a bitwise operator:

Bitwise.<<<(1, 2)
# => 4

All bitwise functions only work on integers.