add safe looping

Aspidites/api/convert.pyx

@@ -169,9 +169,9 @@ def cvt_for_loop_decl(s, loc, t):
             m = r.group(1) + ".items()"
         else:
             m = t[4]
-        s = str(t[3] + "".join(t[:3]) + " in " + m + lit_colon).encode("UTF-8")
+        s = str(t[3] + "".join(t[:3]) + " in __maybe(__safeLoop, " + m + end + lit_colon).encode("UTF-8")
     else:
-        s = str(t[1] + t[0] + " in " + t[2] + lit_colon).encode("UTF-8")
+        s = str(t[1] + t[0] + " in __maybe(__safeLoop, " + t[2] + end + lit_colon).encode("UTF-8")
     return s.decode("UTF-8")
 
 

Aspidites/api/math.pyx

@@ -21,7 +21,7 @@ class Undefined:
     """A monad for a failed programmatic unit; like NoneType but hashable.
     Falsy singleton acts as an absorbing element for division."""
 
-    __slots__ = ("__weakref__", "__instance__", "func", "args", "kwargs")
+    __slots__ = ("__weakref__", "__instance__", "_consumed", "func", "args", "kwargs")
 
     def __hash__(self):
         # noinspection PyUnresolvedReferences
@@ -73,6 +73,16 @@ class Undefined:
         # Undefined has 0 elements
         return 0
 
+    def __iter__(self):
+        return Undefined(self)
+
+    def __next__(self):
+        if not self._consumed:
+            self._consumed = True
+            return Undefined(self)
+        else:
+            raise StopIteration
+
     def __repr__(self):
         if hasattr(self.func, "__name__"):
             r = (
@@ -91,6 +101,7 @@ class Undefined:
         self.func = func
         self.args = args
         self.kwargs = kwargs
+        self._consumed = False
 
 
 def SafeSlice(x: Any, start=None, stop=None, step=None):
@@ -100,6 +111,9 @@ def SafeSlice(x: Any, start=None, stop=None, step=None):
         return x[start:stop:step]
 
 
+def SafeLoop(x: Any):
+    return (i for i in x)
+
 # noinspection PyPep8Naming,PyProtectedMember,PyUnresolvedReferences
 def SafeFactorial(a: Any) -> Any:
     if a < 0 or isnan(a) or isinf(a) or isinstance(a, (float, complex)):

Aspidites/api/templates.pyx

@@ -159,7 +159,7 @@ from Aspidites._vendor.pyrsistent import pset as __pset,pmap as __pmap,pvector a
 from Aspidites.woma import *
 from Aspidites._vendor import take,drop,takelast,droplast,consume,nth,first_true,iterate,padnone,ncycles,repeatfunc,grouper,group_by,roundrobin,partition,splitat,splitby,powerset,pairwise,iter_suppress,flatten,accumulate,reduce,filterfalse,zip_longest,chain,combinations,cycle,dropwhile,islice,repeat,starmap,takewhile,tee,call,apply,flip,curry,curried,zipwith,foldl,foldr,unfold,Capture,Strict,OneOf,AllOf,NoneOf,Not,Each,EachItem,Some,Between,Length,Contains,Regex,Check,InstanceOf,SubclassOf,Arguments,Returns,Transformed,At,Object,match as __match,_
 from Aspidites.api.monads import Maybe as __maybe,Surely as __surely
-from Aspidites.api.math import Undefined as __undefined,SafeSlice as __safeSlice,SafeDiv as __safeDiv,SafeMul as __safeMul,SafeAdd as __safeAdd,SafeSub as __safeSub,SafeExp as __safeExp,SafeMod as __safeMod,SafeFloorDiv as __safeFloorDiv,SafeUnaryAdd as __safeUnaryAdd,SafeUnarySub as __safeUnarySub,SafeFactorial as __safeFactorial
+from Aspidites.api.math import Undefined as __undefined,SafeSlice as __safeSlice,SafeLoop as __safeLoop,SafeDiv as __safeDiv,SafeMul as __safeMul,SafeAdd as __safeAdd,SafeSub as __safeSub,SafeExp as __safeExp,SafeMod as __safeMod,SafeFloorDiv as __safeFloorDiv,SafeUnaryAdd as __safeUnaryAdd,SafeUnarySub as __safeUnarySub,SafeFactorial as __safeFactorial
 from Aspidites._vendor.contracts import contract as __contract,new_contract as __new_contract,check
 from Aspidites._vendor.RestrictedPython.Guards import safe_builtins as __safe_builtins
 from Aspidites._vendor.RestrictedPython.compile import compile_restricted as compile