# Horus: anonymous function to standalone module
[](https://hex.pm/packages/horus/)
[](https://github.com/rabbitmq/horus/actions/workflows/test.yaml)
[](https://codecov.io/gh/rabbitmq/horus)
Horus is a library that extracts an anonymous function's code and creates a
standalone version of it in a new module at runtime.
The goal is to have a storable and transferable function which does not depend
on the availability of the module that defined it.
<img align="right" height="150" src="/doc/horus-logo.svg">
## How does it work?
To achieve that goal, Horus extracts the assembly code of the anonymous
function and creates a standalone Erlang module based on it. This module can be
stored, transfered to another Erlang node and executed anywhere without the
presence of the initial anonymous function's module.
## Project maturity
Horus is still under active development and should be considered *Alpha* at
this stage.
## Documentation
* A short tutorial in the [Getting started](#getting-started) section below
* [Documentation and API reference](https://rabbitmq.github.io/horus/)
## Getting started
### Add as a dependency
Add Horus as a dependency of your project:
Using Rebar:
```erlang
%% In rebar.config
{deps, [{horus, "0.2.1"}]}.
```
Using Erlang.mk:
```make
# In your Makefile
DEPS += horus
dep_horus = hex 0.2.1
```
Using Mix:
```elixir
# In mix.exs
defp deps do
[
:horus, "0.2.1"}
]
end
```
### Extract an anonymous function
To extract an anonymous function, use `horus:to_standalone_fun/1`:
```erlang
Fun = fun() ->
do_something_fancy()
end,
StandaloneFun = horus:to_standalone_fun(Fun).
```
It works with references to regular functions are well:
```erlang
Log = fun logger:info/2,
StandaloneLog = horus:to_standalone_fun(Log).
```
### Execute a standalone function
Once extracted, the function can be stored as an Erlang binary, or transfered
to a remote Erlang node. You then use `horus:exec/2` to execute it:
```erlang
receive
{standalone_fun, StandaloneLog} ->
horus:exec(
StandaloneLog,
["~p received and executed function", [self()]])
end.
```
## How to build
### Build
```
rebar3 compile
```
### Build documentation
```
rebar3 edoc
```
### Test
```
rebar3 xref
rebar3 eunit
rebar3 ct --sname ct
rebar3 as test dialyzer
```
## Copyright and License
© 2021-2023 VMware, Inc. or its affiliates.
This work is dual-licensed under the Apache License 2.0 and the Mozilla Public
License 2.0. You can choose between one of them if you use this work.
SPDX-License-Identifier: Apache-2.0 OR MPL-2.0
