Grain in WebAssembly
Grain is a functional programming language that is designed specifically to compile to WebAssembly. We have enjoyed using it because of its intuitive syntax and great tooling.
Available Implementations
There is one official implementation of Grain
Usage
Grain can be used in the browser. It also supports WASI, so it can be used for the Fermyon Platform (Wagi and Spin) or with commandline runners like Wasmtime.
Pros and Cons
Things we like:
- Easy to learn
- Good toolchain
- Good documentation
We’re neutral about:
- Compiled object size.
- Execution speed.
Things we’re not big fans of:
- Not a lot of third party libraries yet
Example
All of our examples follow a documented pattern using common tools.
To use Grain, you will need to install the Grain toolkit.
Start with a hello.gr
file:
print("content-type: text/plain\n")
print("\n)
print("Hello, World!")
Compile the program with the grain
compiler:
$ grain hello.gr
The above will produce a hello.gr.wasm
file. As usual, you can run wasmtime hello.gr.wasm
to see the output. The first time you compile a grain application, it will take a long time. After that, compiling is much faster.
To run the WebAssembly app with Spin, create a spin.toml
file:
spin_version = "1"
authors = ["Fermyon Engineering <engineering@fermyon.com>"]
description = "Grain example."
name = "spin-grain"
trigger = { type = "http", base = "/" }
version = "1.0.0"
[[component]]
id = "grain-hello"
source = "hello.gr.wasm"
[component.trigger]
route = "/"
# Spin components written in Grain use the Wagi HTTP executor
executor = { type = "wagi" }
From there, you can use spin up
to start a server, and see the results on http://localhost:3000
.
Learn More
Here are some great resources:
- The official Hello World example
- An InfoWorld article on the basics of Grain
- An example Wagi application in Grain
- A production-grade Wagi file server in Grain
- A French-language walk-thru video of Grain, Wagi, and Wasmer