# Orb: Write WebAssembly with Elixir
[Docs](https://hexdocs.pm/orb) | [Examples](https://github.com/RoyalIcing/Orb/tree/main/examples)
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Write WebAssembly with the power of Elixir as your compiler:
- Use Elixir’s **module system** to break problems down and then compose them together.
- Chain function calls together with the **pipe `|>` operator**.
- Publish reusable code with the [**Hex package manager**](https://hex.pm).
- **Write unit tests** using [Elixir’s built-in ExUnit](https://hexdocs.pm/ex_unit/ExUnit.html).
- Reduce boilerplate with Elixir’s **powerful macro system**.
- **Run dynamic Elixir code at compile time** e.g. talk to the rest of your Elixir application, or make network requests.
- **Compile modules on-the-fly** e.g. use feature flags to conditionally compile code paths or enable particular WebAssembly instructions, creating a custom “tree shaken” WebAssembly module per user.
## Installation
Add `orb` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:orb, "~> 0.0.34"}
]
end
```
## Example
```elixir
defmodule CalculateMean do
use Orb
global do
@tally 0
@count 0
end
defw insert(n: I32) do
@tally = @tally + n
@count = @count + 1
end
defw calculate_mean(), I32 do
@tally / @count
end
end
```
This can be converted to WebAssembly text format (wat):
```elixir
Orb.to_wat(CalculateMean)
# """
# (module $CalculateMean
# (global $count (mut i32) (i32.const 0))
# (global $tally (mut i32) (i32.const 0))
# (func $insert (export "insert") (param $element i32)
# (i32.add (global.get $count) (i32.const 1))
# (global.set $count)
# (i32.add (global.get $tally) (local.get $element))
# (global.set $tally)
# )
# (func $calculate_mean (export "calculate_mean") (result i32)
# (i32.div_s (global.get $tally) (global.get $count))
# )
# )
# """
```
You can then execute it in Elixir with [OrbWasmtime](https://github.com/RoyalIcing/OrbWasmtime):
```elixir
alias OrbWasmtime.Instance
# Run above example
inst = Instance.run(CalculateMean)
Instance.call(inst, :insert, 4)
Instance.call(inst, :insert, 5)
Instance.call(inst, :insert, 6)
assert Instance.call(inst, :calculate_mean) == 5
```
Note there is [another excellent Elixir Wasmtime wrapper out there called Wasmex](https://github.com/tessi/wasmex), you may want to check that out too.
## Composing modules
You can compose modules together using `Orb.include/1`:
```elixir
defmodule Math do
use Orb
defw square(n: I32), I32 do
n * n
end
end
defmodule SomeOtherModule do
use Orb
Orb.include(Math)
defw magic(), I32 do
Math.square(3)
end
end
```
## Use cases
- Parsers
- State machines
- Formatters & string builders
- HTTP endpoint that can be deployed agnostically to the server or edge.
- Interactive UI controls
- Write a HTML component and run it in:
- Phoenix LiveView & dead views
- In the browser using `<wasm-html>` custom element
- LiveView and its server rendering is a fantastic default, but the latency can be noticeable for certain UI interactions. With Orb you could use Elixir to write a WebAssembly module that then runs in the user’s browser.
- Animation that runs fast in the browser and also works on the server
- Code generators
## Why WebAssembly?
- It runs on all of today’s major platforms: browser, server, edge, mobile, laptop, tablet, desktop.
- Universal/isomorphic components (ones that run on the server and browser) are possible in React and Next.js, but they have many different flavours and can get pretty complex for a system that was meant to be declarative.
- Like HTML and CSS it’s backwards compatible, which means WebAssembly you author today will be guaranteed to still work in a decade or longer.
- It’s memory-safe and sandboxed. It can’t read memory outside of itself, only what has been explicitly passed into it. It can even be timeboxed to run for a maximum duration.
- It’s fast.
## Why develop Orb in Elixir?
Here are the reasons I chose to write Orb in Elixir.
- Established language:
- Has package manager.
- Has composable modules with `alias` & `use`.
- Has syntax highlighting in IDEs, GitHub, and in highlighting libraries.
- Has language server with autocomplete.
- Has documentation system.
- Has unit test library.
- Has CI integration.
- Has linting.
- Integrates with native libraries in Rust and Zig.
- Has upcoming type system.
- Established frameworks:
- Can integrate with Phoenix LiveView.
- Can connect to cloud, databases.
- Can integrate with Rust.
- Community that is friendly and collaborative.
- Can be extended with additional functions and macros:
- Unlike say C’s basic string-inserting preprocessor, Elixir is a full programming language without constraints.
- We can read files or the network and then generate code.
- You can create your own DSL. Want to enforce immutable-style programming? Want to add pattern matching? Design your own DSL on top of Orb for it.
