# Mapped type expression is not supported Rule ``arkts-no-mapped-types`` **Severity: error** ArkTS does not support mapped types. Use other language idioms and regular classes to achieve that same behavior. ## TypeScript ``` type OptionsFlags = { [Property in keyof Type]: boolean } ``` ## ArkTS ``` class C { n: number = 0 s: string = "" } class CFlags { n: boolean = false s: boolean = false } ```