/**
 * Some programmatic errors are only detectable at runtime
 * (for instance trying to setup a <code>HashSet</code> of <code>Option&lt;number[]&gt;</code>: you
 * can't reliably compare a <code>number[]</code> therefore you can't compare
 * an <code>Option&lt;number[]&gt;</code>.. but we can't detect this error at compile-time
 * in typescript). So when we detect them at runtime, prelude.ts throws
 * an exception by default.
 * This function allows you to change that default action
 * (for instance, you could display an error message in the console,
 * or log the error)
 *
 * You can reproduce the issue easily by running for instance:
 *
 *     HashSet.of(Option.of([1]))
 *     => throws
 */
export declare function setContractViolationAction(action: (msg: string) => void): void;
/**
 * @hidden
 */
export declare function reportContractViolation(msg: string): void;
/**
 * @hidden
 */
export declare function contractTrueEquality(context: string, ...vals: Array<any>): void;