IEx v1.3.4 IEx.Helpers View Source
Welcome to Interactive Elixir. You are currently
seeing the documentation for the module IEx.Helpers
which provides many helpers to make Elixir’s shell
more joyful to work with.
This message was triggered by invoking the helper h()
,
usually referred to as h/0
(since it expects 0 arguments).
You can use the h
function to invoke the documentation
for any Elixir module or function:
h Enum
h Enum.map
h Enum.reverse/1
You can also use the i
function to introspect any value
you have in the shell:
i "hello"
There are many other helpers available:
b/1
- prints callbacks info and docs for a given modulec/1
- compiles a file into the current directoryc/2
- compiles a file to the given pathcd/1
- changes the current directoryclear/0
- clears the screenflush/0
- flushes all messages sent to the shellh/0
- prints this help messageh/1
- prints help for the given module, function or macroi/1
- prints information about the given data typeimport_file/1
- evaluates the given file in the shell’s contextl/1
- loads the given module’s beam codels/0
- lists the contents of the current directoryls/1
- lists the contents of the specified directorynl/2
- deploys local beam code to a list of nodespid/1
- creates a PID from a stringpid/3
- creates a PID with the 3 integer arguments passedpwd/0
- prints the current working directoryr/1
- recompiles the given module’s source filerecompile/0
- recompiles the current projectrespawn/0
- respawns the current shells/1
- prints spec informationt/1
- prints type informationv/0
- retrieves the last value from the historyv/1
- retrieves the nth value from the history
Help for all of those functions can be consulted directly from
the command line using the h
helper itself. Try:
h(v/0)
To learn more about IEx as a whole, just type h(IEx)
.
Link to this section Summary
Functions
Prints the documentation for the given callback function
Compiles the given files
Changes the current working directory to the given path
Clears the console screen
Flushes all messages sent to the shell and prints them out
Prints the documentation for IEx.Helpers
Prints the documentation for the given module or for the given function/arity pair
Prints information about the given data type
Evaluates the contents of the file at path
as if it were directly typed into
the shell
Similar to import_file
but only imports it if it is available
Calls import/2
with the given arguments, but only if the module is available
Loads the given module’s beam code (and ensures any previous old version was properly purged before)
Produces a simple list of a directory’s contents
Deloys a given module’s beam code to a list of nodes
Creates a PID from string
Creates a PID with 3 non negative integers passed as arguments to the function
Prints the current working directory
Recompiles and reloads the given module
Recompiles the current Mix application
Respawns the current shell by starting a new shell process
Prints the specs for the given module or for the given function/arity pair
Prints the types for the given module or for the given function/arity pair
Retrieves the nth expression’s value from the history
Link to this section Functions
Prints the documentation for the given callback function.
It also accepts single module argument to list all available behaviour callbacks.
Examples
b(Mix.Task.run/1)
b(Mix.Task.run)
b(Dict)
Compiles the given files.
It expects a list of files to compile and an optional path to write the compiled code to (defaults to the current directory). When compiling one file, there is no need to wrap it in a list.
It returns the name of the compiled modules.
If you want to recompile an existing module, check r/1
instead.
Examples
c ["foo.ex", "bar.ex"], "ebin"
#=> [Foo, Bar]
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.
Flushes all messages sent to the shell 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
h(Enum)
#=> Prints documentation for Enum
It also accepts functions in the format fun/arity
and module.fun/arity
, for example:
h receive/1
h Enum.all?/2
h Enum.all?
Prints information about the given data type.
Evaluates the contents of the file at path
as if it were directly typed into
the shell.
path
has to be a literal string. path
is automatically expanded via
Path.expand/1
.
Non-existent files
By default, import_file/1
fails when the given file does not exist. However,
since this macro 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 is why an :optional
option can be passed to import_file/1
. The
default value of this option is false
, meaning that an exception will be
raised if the given file is missing. If :optional
is set to true
, missing
files will be ignored and import_file/1
will just compile to nil
.
Examples
# ~/file.exs
value = 13
# in the shell
iex(1)> import_file "~/file.exs"
13
iex(2)> value
13
iex(3)> import_file "nonexisting.file.ex", optional: true
nil
Similar to import_file
but only imports it if it is available.
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 filesystem and you want to tell the VM to load it.
Produces a simple list of a directory’s contents.
If path
points to a file, prints its full path.
Deloys 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
nl(HelloWorld)
#=> {:ok, [{:node1@easthost, :loaded, HelloWorld},
{:node1@westhost, :loaded, HelloWorld}]}
nl(NoSuchModuleExists)
#=> {:error, :nofile}
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>
Prints the current working directory.
Recompiles and reloads the given module
.
Please note that all the modules defined in the same
file as module
are recompiled and reloaded.
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 typespecs and docs are loaded from the .beam file (they are not loaded in memory with the module because there is no need for them to be in memory), they are not reloaded when you reload the module.
Recompiles the current Mix application.
This helper only works when IEx is started with a Mix
project, for example, iex -S mix
. The application is
not restarted after compilation, which means any long
running process may crash as the code is updated but the
state does not go through the proper code changes callback.
In any case, the supervision tree should notice the failure
and restart such servers.
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.
Respawns the current shell by starting a new shell process.
Returns true
if it worked.
Prints the specs for the given module or for the given function/arity pair.
Examples
s(Enum)
s(Enum.all?)
s(Enum.all?/2)
s(is_atom)
s(is_atom/1)
Prints the types for the given module or for the given function/arity pair.
Examples
t(Enum)
t(Enum.t/0)
t(Enum.t)
Retrieves the nth expression’s value from the history.
Use negative values to look up expression values relative to the current one. For instance, v(-1) returns the result of the last evaluated expression.