Elixir v1.9.2 Function View Source
A set of functions for working with functions.
There are two types of captured functions: external and local.
External functions are functions residing in modules that are captured
with &/1
, such as &String.length/1
. Local functions are anonymous functions
defined with fn/1
or with the capture operator &/1
using &1
, &2
,
and so on as replacements.
Link to this section Summary
Functions
Captures the given function.
Returns a keyword list with information about a function.
Returns a specific information about the function.
Link to this section Types
Specs
information() :: :arity | :env | :index | :module | :name | :new_index | :new_uniq | :pid | :type | :uniq
Link to this section Functions
Specs
Captures the given function.
Inlined by the compiler.
Examples
iex> Function.capture(String, :length, 1)
&String.length/1
Specs
info((... -> any())) :: [{information(), term()}]
Returns a keyword list with information about a function.
The returned keys (with the corresponding possible values) for all types of functions (local and external) are the following:
:type
-:local
(for anonymous functions) or:external
(for named functions).:module
- an atom which is the module where the function is defined when anonymous or the module which the function refers to when it's a named function.:arity
- (integer) the number of arguments the function is to be called with.:name
- (atom) the name of the function.:env
- a list of the environment or free variables. For named functions, the returned list is always empty.
When fun
is an anonymous function (that is, the type is :local
), the following
additional keys are returned:
:pid
- PID of the process that originally created the function.:index
- (integer) an index into the module function table.:new_index
- (integer) an index into the module function table.:new_uniq
- (binary) a unique value for this function. It's calculated from the compiled code for the entire module.:uniq
- (integer) a unique value for this function. This integer is calculated from the compiled code for the entire module.
Note: this function must be used only for debugging purposes.
Inlined by the compiler.
Examples
iex> fun = fn x -> x end
iex> info = Function.info(fun)
iex> Keyword.get(info, :arity)
1
iex> Keyword.get(info, :type)
:local
iex> fun = &String.length/1
iex> info = Function.info(fun)
iex> Keyword.get(info, :type)
:external
iex> Keyword.get(info, :name)
:length
Specs
info((... -> any()), item) :: {item, term()} when item: information()
Returns a specific information about the function.
The returned information is a two-element tuple in the shape of
{info, value}
.
For any function, the information asked for can be any of the atoms
:module
, :name
, :arity
, :env
, or :type
.
For anonymous functions, there is also information about any of the
atoms :index
, :new_index
, :new_uniq
, :uniq
, and :pid
.
For a named function, the value of any of these items is always the
atom :undefined
.
For more information on each of the possible returned values, see
info/1
.
Inlined by the compiler.
Examples
iex> f = fn x -> x end
iex> Function.info(f, :arity)
{:arity, 1}
iex> Function.info(f, :type)
{:type, :local}
iex> fun = &String.length/1
iex> Function.info(fun, :name)
{:name, :length}
iex> Function.info(fun, :pid)
{:pid, :undefined}