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

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

ast.py

@@ -8,10 +8,6 @@ from typing import Union
 from enum import Enum
 from sympy import Symbol
 
-from lenses import lens
-
-import funcy as fn
-
 VarKind = Enum("VarKind", ["x", "u", "w"])
 str_to_varkind = {"x": VarKind.x, "u": VarKind.u, "w": VarKind.w}
 dt_sym = Symbol('dt', positive=True)
@@ -51,7 +47,7 @@ class NaryOpSTL(namedtuple('NaryOp', ['args'])):
         if n == 1:
             return "{}".format(self.args[0])
         elif self.args:
-            rep = "({})" + " {op} ({})"*(len(self.args) - 1)
+            rep = " {op} ".join(["({})"]*(len(self.args) - 1))
             return rep.format(*self.args, op=self.OP)
         else:
             return ""
@@ -88,57 +84,3 @@ class Neg(namedtuple('Neg', ['arg'])):
 
     def children(self):
         return [self.arg]
-
-
-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_()