lively.verify

Experimental support for interactively verifying JavaScript

Example

Given a simple JavaScript max function, we can add pre- and post-conditions using special pseudo-calls to requires and ensures with boolean expressions.

function max(a, b) {
  requires(typeof(a) == "number");
  requires(typeof(b) == "number");
  ensures(max(a,b) >= a);
  if (a >= b) {
    return a;
  } else {
    return b;
  }
}

These expressions will then be statically verified with respect to the function body with an SMT solver. A tiny hand-written example of an SMT constraint system that verified the above function is given here.

Interactive Tools

The tool support will be improved in the future but the first step is a verification workspace which allows inspection of verificaiton results including potential counter-examples.