Braid

A functional language with Reason-like syntax that compiles to Go.

I’m working on a language I’m calling Braid, an ML-like language that compiles to Go. Braid’s syntax is heavily inspired by Reason, itself a more C-like syntax on top of OCaml. So really I’m writing a language that aims to be fairly similar to OCaml in what it can do, but visually a bit closer to Go. I’m not trying to reimplement OCaml or Reason 1:1 on top of Go, but build something sharing many of the same concepts.

I've written some more about it on my Braid dev blog.

Status

Very, very alpha.

Goals

• Pair an OCaml-like language with the benefits of the Go platform (speed, concurrency, static binaries, a healthy ecosystem)
• Bring powerful FP concepts to Go
• Get around Go's lack of generics
• Interop with Go code
• Ability to use Go stdlib

Non-goals

• Performance matching idiomatic Go
• Just reimplementing Reason on top of Go

Language overview

Consider anything ticked off to exist in the language, but be barely usable.

• Record types
• Variant types
• If-expressions
• Importing Go functions and types
• Immutability by default
• Hindley-Milner type inference
• Type annotations
• Implicit return
• Multiple return
• Modules
• Pattern matching
• Currying
• Typeclasses/traits
• Concurrency
• Infix operators

Braid supports records and variants:

type Person = {
  name: string,
  age: int64,
}

type Fruit = 
  | Peach
  | Plum
  | Pear

type Option ('a) =
  | Some ('a)
  | None
  
let result = Some("it worked")

Braid attempts to support significant newlines, meaning no ; required — however this is probably broken in a lot of cases right now.

A full example:

module Main

// record type
type Payload = {
  name: string,
  data: string,
}

// go interop - external functions must be annotated
extern func println = "fmt.Println" (s: string) -> ()
extern func printf1 = "fmt.Printf" (s: string, arg1:string) -> ()

/* func to add cheesiness to any two items */
let cheesy = (item, item2) {
  item ++ " and " ++ item2 ++ " with cheese please"
}

let main = {
  // nested functions
  let something = {
    4 + 9
  }
  let a = something()
  let yumPizza = cheesy("pineapple", "bbq sauce")
  println(yumPizza)
  // calling a go function
  printf1("Woo I can print %s\n", "6")
  let b = Payload{name: "greeting", data: "hi"}
  println(b.name)
}

Trying it out

Grab the correct Braid package for your platform from the releases, extract the braid binary, and run it.

./braid filename.bd

This will compile your Braid file to Go and print the resulting Go source code to stdout.

./braid filename.bd > main.go

You can redirect this into a file if you like.

Developing

Requirements

• Go 1.10
• GB
• goimports

Building

Making sure Go and GB are in your path, clone the Braid repository into a new directory:

git clone https://github.com/joshsharp/braid.git

Enter the new braid directory and fetch the requirements:

cd braid
gb vendor restore

Make sure the vendored dependencies are built (you'll only need to do this once):

cd vendor
gb build all

Use the makefile at src/braid/Makefile to build and run Braid:

cd ../src/braid
make run file=examples/example.bd

FAQ

Will Braid support X?

I don't know yet. I'm open to proposals, provided you help me do the work.

Do you even know what you're doing?

Nope, not at all. I have no formal background in this stuff. Really I'm doing it for fun. I'd love to see it reach maturity, because I want to use it myself. But I'll need a lot of help if it's to get that far.

Contributing

Contribution guidelines

Your help makes Braid better! I welcome pull requests, bug fixes, and issue reports.

Before proposing a change, please first create an issue to discuss your proposal.

License

Licensed under the MIT License.