TypeScript code snippets for discrimated unions and unique types

typescript.code-snippets

{
	// Place your global snippets here. Each snippet is defined under a snippet name and has a scope, prefix, body and
	// description. Add comma separated ids of the languages where the snippet is applicable in the scope field. If scope
	// is left empty or omitted, the snippet gets applied to all languages. The prefix is what is
	// used to trigger the snippet and the body will be expanded and inserted. Possible variables are:
	// $1, $2 for tab stops, $0 for the final cursor position, and ${1:label}, ${2:another} for placeholders.
	// Placeholders with the same ids are connected.
	// Example:
	// "Print to console": {
	// 	"scope": "javascript,typescript",
	// 	"prefix": "log",
	// 	"body": [
	// 		"console.log('$1');",
	// 		"$2"
	// 	],
	// 	"description": "Log output to console"
	// }

	"Unique Typed Constant": {
		"scope": "typescript,typescriptreact",
		"prefix": ["utypeconst", "uniquetypedconstant"],
		"body": [
			"const ${1:Type}Symbol = Symbol(\"${1}\");",
			"export interface ${1} {",
			"\treadonly type: typeof ${1}Symbol;",
			"}",
			"export const ${1}: ${1} = { type: ${1}Symbol };",
			"export function is${1}(${3:value}: ${2:unknown}): ${3} is ${1} {",
			"\treturn (${3} as { type?: symbol }).type === ${1}Symbol;",
			"}"
		]
	},

	"Unique Type": {
		"scope": "typescript,typescriptreact",
		"prefix": ["utype", "uniquetype"],
		"body": [
			"const ${1:Type}Symbol = Symbol(\"${1}\");",
			"export interface ${1} {",
			"\treadonly type: typeof ${1}Symbol;",
			"}",
			"export const ${1}: () => ${1} = () => ({",
			"\ttype: ${1}Symbol,",
			"});",
			"export function is${1}(${3:value}: ${2:unknown}): ${3} is ${1} {",
			"\treturn (${3} as { type?: symbol }).type === ${1}Symbol;",
			"}"
		]
	},

	"Discriminated Union": {
		"scope": "typescript,typescriptreact",
		"prefix": ["dunion", "discriminatedunion"],
		"body": [
			"namespace ${1:Union} {",
			"\t${0}",
			"}",
			"type ${1} =",
			"\t| never",
			"\t;"
		]
	}
}