# Definite assignment assertions are not supported Rule ``arkts-no-definite-assignment`` **Severity: warning** ArkTS does not support definite assignment assertions ``let v!: T`` because they are considered an excessive compiler hint. Use declaration with initialization instead. ## TypeScript ``` let x!: number // Hint: x will be initialized before usage initialize() function initialize() { x = 10 } console.log("x = " + x) ``` ## ArkTS ``` function initialize() : number { return 10 } let x: number = initialize() console.log("x = " + x) ```