Go Unto Ts (guts)

guts is a tool to convert golang types to typescript for enabling a consistent type definition across the frontend and backend. It is intended to be called and customized as a library, rather than as a command line executable.

See the simple example for a basic usage of the library.

type SimpleType[T comparable] struct {
	FieldString     string
	FieldInt        int
	FieldComparable T
	FieldTime       time.Time
}

Gets converted into

type Comparable = string | number | boolean;

// From main/main.go
interface SimpleType<T extends Comparable> {
    FieldString: string;
    FieldInt: number;
    FieldComparable: T;
    FieldTime: string;
}

How to use it

guts is a library, not a command line utility. This is to allow configuration with code, and also helps with package resolution.

See the simple example for a basic usage of the library. A larger example can be found in the Coder repository.

// Step 1: Create a new Golang parser
golang, _ := guts.NewGolangParser()
// Step 2: Configure the parser
_ = golang.IncludeGenerate("github.com/coder/guts/example/simple")
// Step 3: Convert the Golang to the typescript AST
ts, _ := golang.ToTypescript()
// Step 4: Mutate the typescript AST
ts.ApplyMutations(
    config.ExportTypes, // add 'export' to all top level declarations
)
// Step 5: Serialize the typescript AST to a string
output, _ := ts.Serialize()
fmt.Println(output)

How it works

guts first parses a set of golang packages. The Go AST is traversed to find all the types defined in the packages.

These types are placed into a simple AST that directly maps to the typescript AST.

Using goja, these types are then serialized to typescript using the typescript compiler API.

Generator Opinions

The generator aims to do the bare minimum type conversion. An example of a common opinion, is to create enum lists.

export type Enum = "bar" | "baz" | "foo" | "qux" // <-- Golang type
export const Enums: Enum[] = ["bar", "baz", "foo", "qux"] // <-- Helpful additional generated type

These kinds of opinions can be added with:

ts.ApplyMutations(
	config.EnumLists,
)
output, _ := ts.Serialize()

Helpful notes

An incredible website to visualize the AST of typescript: https://ts-ast-viewer.com/