Returning closures to the user

[breuleux]

If the user defines a function that returns a closure, running it through the VM should return a callable object. In other words, the following should work, and it should print 30:

def f(x):
    def g():
        return x
    return g

g = run(parse(f), [30])
print(g())

The same goes if the user somehow returns a primitive: it should return a callable version of the primitive.

At the moment, the VM returns an internal Closure type or the raw Primitive.

[abergeron]

We would need to do some post-processing on the returned value. It shouldn't be too hard.

[breuleux]

I'm going to work on that now, because I need it to test the output of the Grad transform.