change yaml spec to + move ast utilities + drop numpy dependency

yaml spec now supports attaching meta data to specs such as pri or stl

utils.py

@@ -0,0 +1,57 @@
+from lenses import lens
+import funcy as fn
+
+from stl.ast import LinEq, And, Or, NaryOpSTL
+
+def walk(stl, bfs=False):
+    """Walks Ast. Defaults to DFS unless BFS flag is set."""
+    pop = deque.popleft if bfs else deque.pop
+    children = deque([stl])
+    while len(children) != 0:
+        node = pop(children)
+        yield node
+        children.extend(node.children())
+
+
+def tree(stl):
+    return {x:set(x.children()) for x in walk(stl) if x.children()}
+
+
+def type_pred(*args):
+    ast_types = set(args)
+    return lambda x: type(x) in ast_types
+
+
+def _child_lens(psi, focus):
+    if psi is None:
+        return
+    if isinstance(psi, NaryOpSTL):
+        for j, _ in enumerate(psi.args):
+            yield focus.args[j]
+    else:
+        yield focus.arg
+
+
+def ast_lens(phi:"STL", bind=True, *, pred) -> lens:
+    tls = list(fn.flatten(_ast_lens(phi, pred=pred)))
+    tl = lens().tuple_(*tls).each_()
+    return tl.bind(phi) if bind else tl
+
+
+def _ast_lens(phi, *, pred, focus=lens()):
+    psi = focus.get(state=phi)
+    ret_lens = [focus] if pred(psi) else []
+
+    if isinstance(psi, LinEq):
+        return ret_lens
+
+    child_lenses = list(_child_lens(psi, focus=focus))
+    ret_lens += [_ast_lens(phi, pred=pred, focus=cl) for cl in child_lenses]
+    return ret_lens
+
+
+lineq_lens = fn.partial(ast_lens, pred=type_pred(LinEq))
+and_or_lens = fn.partial(ast_lens, pred=type_pred(And, Or))
+
+def terms_lens(phi:"STL", bind=True) -> lens:
+    return lineq_lens(phi, bind).terms.each_()