Generic Constraint With Conditional Type

export function pick<T extends object,K extends keyof T>(obj:T,keys:K[]):Pick<T,K>{const result={} as Pick<T,K>;for(const k of keys)result[k]=obj[k];return result;}export function omit<T extends object,K extends keyof T>(obj:T,keys:K[]):Omit<T,K>{const result={...obj};for(const k of keys)delete result[k];return result;}export type DeepPartial<T>={[K in keyof T]?:T[K]extends object?DeepPartial<T[K]>:T[K]};export type NonEmptyArray<T>=[T,...T[]];export function first<T extends NonEmptyArray<unknown>>(arr:T):T[number]{return arr[0];}