Prints the documentation for the given callback function.

It also accepts single module argument to list all available behaviour callbacks.

Examples

iex> b(Mix.Task.run/1)
iex> b(Mix.Task.run)
iex> b(GenServer)

Sets up a breakpoint in the AST of shape Module.function/arity with the given number of stops.

See IEx.break!/4 for a complete description of breakpoints in IEx.

Examples

break! URI.decode_query/2

Sets up a breakpoint in module, function and arity with the given number of stops.

See IEx.break!/4 for a complete description of breakpoints in IEx.

Examples

break! URI, :decode_query, 2

Prints all breakpoints to the terminal.

A shortcut for continue/0.

Compiles the given files.

It expects a list of files to compile and an optional path to write the compiled code to. By default files are in-memory compiled. To write compiled files to the current directory, "." can be given.

It returns the names of the compiled modules.

If you want to recompile an existing module, check r/1 instead.

Remote compilation

When compiling code, warnings and errors may be printed to standard error. However, when connecting to a remote node, the standard error output is not redirected to the client. This means that compilation failures will be written to the logs or the output terminal of the machine you connect to.

Examples

In the example below, we pass a directory to where the c/2 function will write the compiled .beam files to. This directory is typically named "ebin" in Erlang/Elixir systems:

iex> c(["foo.ex", "bar.ex"], "ebin")
[Foo, Bar]

When compiling one file, there is no need to wrap it in a list:

iex> c("baz.ex")
[Baz]

Changes the current working directory to the given path.

Clears the console screen.

This function only works if ANSI escape codes are enabled on the shell, which means this function is by default unavailable on Windows machines.

Continues execution of the current process.

This is usually called by sessions started with IEx.pry/0 or IEx.break!/4. This allows the current process to execute until the next breakpoint, which will automatically yield control back to IEx without requesting permission to pry.

If you simply want to move to the next line of the current breakpoint, use n/0 or next/0 instead.

If the running process terminates, a new IEx session is started.

While the process executes, the user will no longer have control of the shell. If you would rather start a new shell, use respawn/0 instead.

Prints a list of all the functions and macros exported by the given module.

Clears out all messages sent to the shell's inbox and prints them out.

Prints the documentation for IEx.Helpers.

Prints the documentation for the given module or for the given function/arity pair.

Examples

iex> h(Enum)

It also accepts functions in the format function/arity and module.function/arity, for example:

iex> h(receive/1)
iex> h(Enum.all?/2)
iex> h(Enum.all?)

Prints information about the data type of any given term.

If no argument is given, the value of the previous expression is used.

Examples

iex> i(1..5)

Will print:

Term
  1..5
Data type
  Range
Description
  This is a struct. Structs are maps with a __struct__ key.
Reference modules
  Range, Map

Injects the contents of the file at path.

This would be the equivalent of getting all of the file contents and pasting it all at once in IEx and executing it.

By default, the contents of a .iex.exs file in the same directory as you are starting IEx are automatically imported. See the section for ".iex.exs" in the IEx module docs for more information.

path has to be a literal string and is automatically expanded via Path.expand/1.

Examples

# ~/file.exs
value = 13

# in the shell
iex(1)> import_file("~/file.exs")
13
iex(2)> value
13

Similar to import_file but only imports the file if it is available.

By default, import_file/1 fails when the given file does not exist. However, since import_file/1 is expanded at compile-time, it's not possible to conditionally import a file since the macro is always expanded:

# This raises a File.Error if ~/.iex.exs doesn't exist.
if "~/.iex.exs" |> Path.expand() |> File.exists?() do
  import_file("~/.iex.exs")
end

This macro addresses this issue by checking if the file exists or not in behalf of the user.

Calls import/2 with the given arguments, but only if the module is available.

This lets you put imports in .iex.exs files (including ~/.iex.exs) without getting compile errors if you open a console where the module is not available.

Example

# In ~/.iex.exs
import_if_available(Ecto.Query)

Loads the given module's BEAM code (and ensures any previous old version was properly purged before).

This function is useful when you know the bytecode for module has been updated in the file system and you want to tell the VM to load it.

Prints a list of the given directory's contents.

If path points to a file, prints its full path.

A shortcut for next/0.

Goes to the next line of the current breakpoint.

This is usually called by sessions started with IEx.break!/4. If instead of the next line you want to move to the next breakpoint, call continue/0 instead.

While the process executes, the user will no longer have control of the shell. If you would rather start a new shell, use respawn/0 instead.

Deploys a given module's BEAM code to a list of nodes.

This function is useful for development and debugging when you have code that has been compiled or updated locally that you want to run on other nodes.

The node list defaults to a list of all connected nodes.

Returns {:error, :nofile} if the object code (i.e. ".beam" file) for the module could not be found locally.

Examples

iex> nl(HelloWorld)
{:ok,
 [
   {:node1@easthost, :loaded, HelloWorld},
   {:node1@westhost, :loaded, HelloWorld}
 ]}

iex> nl(NoSuchModuleExists)
{:error, :nofile}

Opens the current prying location.

This command only works inside a pry session started manually via IEx.pry/0 or a breakpoint set via IEx.break!/4. Calling this function during a regular IEx session will print an error.

Keep in mind the open/0 location may not exist when prying precompiled source code, such as Elixir itself.

For more information and to open any module or function, see open/1.

Opens the given module, module.function/arity, or {file, line}.

This function uses the ELIXIR_EDITOR environment variable and falls back to EDITOR if the former is not available.

By default, it attempts to open the file and line using the file:line notation. For example, for Sublime Text you can set it as:

ELIXIR_EDITOR="subl"

Which will then try to open it as:

subl path/to/file:line

For Visual Studio Code, once enabled on the command line, you can set it to:

ELIXIR_EDITOR="code --goto"

It is important that you choose an editor command that does not block nor that attempts to run an editor directly in the terminal. Command-line based editors likely need extra configuration so they open up the given file and line in a separate window.

For more complex use cases, you can use the __FILE__ and __LINE__ notations to explicitly interpolate the file and line into the command:

ELIXIR_EDITOR="my_editor +__LINE__ __FILE__"

Since this function prints the result returned by the editor, ELIXIR_EDITOR can be set "echo" if you prefer to display the location rather than opening it.

Keep in mind the location may not exist when opening precompiled source code.

Examples

iex> open(MyApp)
iex> open(MyApp.fun/2)
iex> open({"path/to/file", 1})

@spec pid(binary() | atom()) :: pid()

Creates a PID from string or atom.

Examples

iex> pid("0.21.32")
#PID<0.21.32>

iex> pid("#PID<0.21.32>")
#PID<0.21.32>

iex> pid(:init)
#PID<0.0.0>

@spec pid(non_neg_integer(), non_neg_integer(), non_neg_integer()) :: pid()

Creates a PID with 3 non-negative integers passed as arguments to the function.

Examples

iex> pid(0, 21, 32)
#PID<0.21.32>
iex> pid(0, 64, 2048)
#PID<0.64.2048>

@spec port(binary()) :: port()

Creates a Port from string.

Examples

iex> port("0.4")
#Port<0.4>

@spec port(non_neg_integer(), non_neg_integer()) :: port()

Creates a Port from two non-negative integers.

Examples

iex> port(0, 8080)
#Port<0.8080>
iex> port(0, 443)
#Port<0.443>

Prints the current working directory.

Recompiles and reloads the given module or modules.

Please note that all the modules defined in the same file as modules are recompiled and reloaded. If you want to reload multiple modules, it is best to reload them at the same time, such as in r [Foo, Bar]. This is important to avoid false warnings, since the module is only reloaded in memory and its latest information is not persisted to disk. See the "In-memory reloading" section below.

This function is meant to be used for development and debugging purposes. Do not depend on it in production code.

In-memory reloading

When we reload the module in IEx, we recompile the module source code, updating its contents in memory. The original .beam file in disk, probably the one where the first definition of the module came from, does not change at all.

Since docs, typespecs, and exports information are loaded from the .beam file, they are not reloaded when you invoke this function.

Recompiles the current Mix project or Mix install dependencies.

This helper requires either Mix.install/2 to have been called within the current IEx session or for IEx to be started alongside, for example, iex -S mix.

In the Mix.install/1 case, it will recompile any outdated path dependency declared during install. Within a project, it will recompile any outdated module.

Note this function simply recompiles Elixir modules, without reloading configuration or restarting applications. This means any long running process may crash on recompilation, as changed modules will be temporarily removed and recompiled, without going through the proper code change callback.

If you want to reload a single module, consider using r(ModuleName) instead.

This function is meant to be used for development and debugging purposes. Do not depend on it in production code.

Options

• :force - when true, forces the application to recompile

@spec ref(binary()) :: reference()

Creates a Reference from string.

Examples

iex> ref("0.1.2.3")
#Reference<0.1.2.3>

@spec ref(non_neg_integer(), non_neg_integer(), non_neg_integer(), non_neg_integer()) ::
  reference()

Creates a Reference from its 4 non-negative integers components.

Examples

iex> ref(0, 1, 2, 3)
#Reference<0.1.2.3>

Removes all breakpoints and instrumentation from all modules.

Removes all breakpoints and instrumentation from module.

Resets the number of pending stops in the breakpoint with the given id to zero.

Returns :ok if there is such breakpoint ID. :not_found otherwise.

Note the module remains "instrumented" on reset. If you would like to effectively remove all breakpoints and instrumentation code from a module, use remove_breaks/1 instead.

Resets the number of pending stops in the given module, function and arity to zero.

If the module is not instrumented or if the given function does not have a breakpoint, it is a no-op and it returns :not_found. Otherwise it returns :ok.

Note the module remains "instrumented" on reset. If you would like to effectively remove all breakpoints and instrumentation code from a module, use remove_breaks/1 instead.

Respawns the current shell by starting a new shell process.

Prints VM/runtime information such as versions, memory usage and statistics.

Additional topics are available via runtime_info/1.

For more metrics, info, and debugging facilities, see the Recon project.

Just like runtime_info/0, except accepts topic or a list of topics.

For example, topic :applications will list the applications loaded.

Prints the types for the given module or for the given function/arity pair.

Examples

iex> t(Enum)
@type t() :: Enumerable.t()
@type acc() :: any()
@type element() :: any()
@type index() :: integer()
@type default() :: any()

iex> t(Enum.t/0)
@type t() :: Enumerable.t()

iex> t(Enum.t)
@type t() :: Enumerable.t()

Calls use/2 with the given arguments, but only if the module is available.

This lets you use the module in .iex.exs files (including ~/.iex.exs) without getting compile errors if you open a console where the module is not available.

Example

# In ~/.iex.exs
use_if_available(Phoenix.HTML)

Returns the value of the nth expression in the history.

n can be a negative value: if it is, the corresponding expression value relative to the current one is returned. For example, v(-2) returns the value of the expression evaluated before the last evaluated expression. In particular, v(-1) returns the result of the last evaluated expression and v() does the same.

Examples

iex(1)> "hello" <> " world"
"hello world"
iex(2)> 40 + 2
42
iex(3)> v(-2)
"hello world"
iex(4)> v(2)
42
iex(5)> v()
42

Prints the current location and stacktrace in a pry session.

It expects a radius which chooses how many lines before and after the current line we should print. By default the radius is of two lines:

Location: lib/iex/lib/iex/helpers.ex:79

77:
78:   def recompile do
79:     require IEx; IEx.pry()
80:     if mix_started?() do
81:       config = Mix.Project.config

(IEx.Helpers) lib/iex/lib/iex/helpers.ex:78: IEx.Helpers.recompile/0

This command only works inside a pry session started manually via IEx.pry/0 or a breakpoint set via IEx.break!/4. Calling this function during a regular IEx session will print an error.

Keep in mind the whereami/1 location may not exist when prying precompiled source code, such as Elixir itself.