Defining a Schema for Unique Comma-Separated Literal Strings

const uniqueValues = S.filter((a: Array<unknown>) => a.length === new Set(a).size || "All values must be unique");

const Things = S.Array(S.Literal("foo", "bar", "baz")).pipe(uniqueValues)

const program = Effect.gen(function* () {
  console.log(S.decodeSync(Things)("foo,bar") === ["foo", "bar"])
  console.log(S.encodeSync(Things)(["foo", "bar"]) === "foo,bar")
  S.decodeSync(Things)("foo,foo") // should throw an error
  S.encodeSync(Things)(["foo", "foo"]) // this should be a type error
})