Roadmap

1.1

Some notation that eliminates this:

   ( (checker arg) (value-generator)) => falsey

I'm leaning toward

  (value-generator) =deny=> (checker arg)

A =streams=> notation
Folded prerequisites that work on more than one argument (but still only on one).

Doc strings
A thoroughgoing effort to provide good error messages for syntax (etc.) errors.
A way of marking individual facts as pending, rather than a whole fact statement. Perhaps
```
  (f 33) =someday=> 3
```
XML/TAP format output, like this: https://github.com/arohner/lein-test-out

Typed metaconstants A problem with metaconstants is that you can't say something like
```
   (f ...n...) => (* 2 ...n...)
```
because ...n...'s value is a symbol. It'd be nice if you could give it a type Integer, meaning it'd be assigned an arbitrary (random?) integer.
Reversible checkers.

...movie... => has-favorite-actor? ; instead of (has-favorite-actor? ...movie...) => truthy

(recommendations) => (just ...movie...) ; instead of (recommendations) => [...movie...]