Unintuitive recursive type error in simple code

The following code fails to type
```scheme
(lambda () ((:callback *context*) 10))
```

It infers that the context has to have a `:callback` field of type function:

```
{
  :callback (-> .... number a)
}
```

but what's the full type of that function? the function is called in the same context itself, so the inferred type for the code would be a recursive context.
