marimoiro/cuetsy

Experimental CUE->TypeScript exporter

Installation · Usage

cuetsy

Converting CUE objects to their TypeScript equivalent (highly experimental!)

• CUE makes defining and validating canonical data specification easy
• TypeScript is dominant in the frontend, but cannot natively benefit from this
• CUE types often have direct TypeScript equivalents, so cuetsy can bridge this gap

Example

CUE	TypeScript
DiceFaces: 1 | 2 | 3 | 4 | 5 | 6 @cuetsy(kind="type") Animal: { Name: string Sound: string } @cuetsy(kind="interface") LeggedAnimal: Animal & { Legs: int } @cuetsy(kind="interface") Pets: "Cat" | "Dog" | "Horse" @cuetsy(kind="enum")	export type DiceFaces = 1 | 2 | 3 | 4 | 5 | 6; export interface Animal { Name: string; Sound: string; } export interface LeggedAnimal extends Animal { Legs: number; } export enum Pets { Cat = "Cat", Dog = "Dog", Horse = "Horse", }

Status

Cuetsy is experimental. The following are supported:

• Types
  • Unions
  • Interfaces
  • Enums
• Default const

Installation

Cuetsy can be installed using Go 1.16+

$ go install github.com/grafana/cuetsy/cmd/cuetsy

Usage

cuetsy must be invoked on files as follows:

$ cuetsy [file.cue]

This will create a logically equivalent [file].ts

Alternatively, cuetsy can be used as a library for more customized code generation.

Union Types

CUE	TypeScript	@cuetsy(kind)
Disjunction	Union Type	type

Union types are expressed in CUE and TypeScript nearly the same way, namely a series of disjunctions (a | b | c):

CUE	TypeScript
MyUnion: 1 | 2 | 3 | 4 | 5 | 6 @cuetsy(kind="type")	export type MyUnion = 1 | 2 | 3 | 4 | 5 | 6;

Interfaces

CUE	TypeScript	@cuetsy(kind)
Struct	Interface	interface

TypeScript interfaces are expressed as regular structs in CUE.

Caveats:

• Default generation does not work correctly for optional nested structs. Issue

CUE	TypeScript
MyInterface: { Num: number Text: string List: [...number] Truth: bool } @cuetsy(kind="interface")	export interface MyInterface { List: number[]; Num: number; Text: string; Truth: boolean; }

Inheritance

Interfaces can optionally extend another interface. If a type marked for export as a kind="interface" is unified (whether by & or embedding) with another type marked for export as an interface, it will produce extend in output:

CUE	TypeScript
AInterface: { AField: string } @cuetsy(kind="interface") ByUnifying: AInterface & { BField: int } @cuetsy(kind="interface") ByEmbedding: { AInterface CField: bool } @cuetsy(kind="interface")	export interface AInterface { AField: string; } export interface ByUnifying extends AInterface { BField: number; } export interface ByEmbedding extends AInterface { CField: boolean; }

Enums

CUE	TypeScript	@cuetsy(kind)
Disjunction	String enums, Numeric enums	enum

TypeScript's enums are union types, and are a mostly-exact mapping of what can be expressed with CUE's disjunctions. Disjunctions may contain only string or numeric values.

For string enums, the member names (keys) of the TypeScript enum are automatically inferred as the titled camel-case variant of their string value, but may be explicitly specified using the memberNames attribute. For a numeric enum, memberNames must be specified.

CUE	TypeScript
AutoCamel: "foo" | "bar" @cuetsy(kind="enum") ManualCamel: "foo" | "bar" @cuetsy(kind="enum",memberNames="Foo|Bar") Arbitrary: "foo" | "bar" @cuetsy(kind="enum",memberNames="Zip|Zap") Numeric: 0 | 1 | 2 @cuetsy(kind="enum",memberNames="Zero|One|Two")	export enum AutoCamel { Bar = 'bar', Foo = 'foo', } export enum ManualCamel { Bar = 'bar', Foo = 'foo', } export enum Arbitrary { Zap = 'bar', Zip = 'foo', } export enum Numeric { One = 1, Two = 2, Zero = 0, }

Defaults

CUE	TypeScript
Defaults	const

Cuetsy can optionally generate a const for each type that holds default values. For that, mark CUE Default Values to your type definitions:

CUE	TypeScript
MyUnion: 1 | 2 | *3 @cuetsy(kind="type") MyEnum: "foo" | *"bar" @cuetsy(kind="enum") MyInterface: { num: int | *6 txt: string | *"CUE" enm: MyDisjEnum } @cuetsy(kind="interface")	export type MyUnion = 1 | 2 | 3; export const defaultMyUnion: MyUnion = 3; export enum MyEnum { Bar = 'bar', Foo = 'foo', } export const defaultMyEnum: MyEnum = MyEnum.Bar; export interface MyInterface { enm: MyDisjEnum; num: number; txt: string; } export const defaultMyInterface: Partial<MyInterface> = { enm: MyDisjEnum.Bar, num: 6, txt: 'CUE', };