Merge branch 'jahs-master'

Author: jacobbridges

.travis.yml

@@ -2,15 +2,21 @@ sudo: false
 language: python
 python: 3.5
 env:
+  - TOXENV=codestyle
   - TOXENV=py26
   - TOXENV=py27
   - TOXENV=py33
   - TOXENV=py34
   - TOXENV=py35
   - TOXENV=pypy
-  - TOXENV=pypy3
 install: pip install tox
 script: tox
+matrix:
+  include:
+    - python: 3.6
+      env: TOXENV=py36
+    - python: pypy3
+      env: TOXENV=pypy3
 
 notifications:
   email: false

README.rst

@@ -436,19 +436,13 @@ To install ``fn.py``, simply:
 
 .. code-block:: console
 
-    $ pip install fn
-
-Or, if you absolutely must:
-
-.. code-block:: console
-
-    $ easy_install fn
+    $ pip install fn.py
 
 You can also build library from source
 
 .. code-block:: console
 
-    $ git clone https://github.com/kachayev/fn.py.git
+    $ git clone https://github.com/fnpy/fn.py.git
     $ cd fn.py
     $ python setup.py install
 

fn/immutable/list.py

@@ -47,10 +47,9 @@ def __radd__(self, el):
         return self.cons(el)
 
     def __iter__(self):
-        l = self
-        while l:
-            yield l.head
-            l = l.tail
+        while self:
+            yield self.head
+            self = self.tail
 
     def __len__(self):
         return self._count

fn/iters.py

@@ -58,6 +58,7 @@ def first_true(iterable, default=False, pred=None):
     """
     return next(filter(pred, iterable), default)
 
+
 # widely-spreaded shortcuts to get first item, all but first item,
 # second item, and first item of first item from iterator respectively
 head = first = partial(flip(nth), 0)
@@ -251,6 +252,7 @@ def flatten(items):
         else:
             yield item
 
+
 if version_info[0] == 3 and version_info[1] >= 3:
     from itertools import accumulate
 else:

fn/op.py

@@ -8,6 +8,7 @@
 def _apply(f, args=None, kwargs=None):
     return f(*(args or []), **(kwargs or {}))
 
+
 apply = apply if version_info[0] == 2 else _apply
 
 

fn/recur.py

@@ -1,4 +1,6 @@
-"""Provides decorator to deal with tail calls in recursive function."""
+"""Provides decorators to deal with tail calls in recursive functions."""
+
+from collections import namedtuple
 
 
 class tco(object):
@@ -44,3 +46,90 @@ def __call__(self, *args, **kwargs):
             if callable(act):
                 action = act
             kwargs = result[2] if len(result) > 2 else {}
+
+
+class stackless(object):
+    """Provides a "stackless" (constant Python stack space) recursion
+    decorator for generators.
+
+    Invoking as f() creates the control structures. Within a
+    function, only use `yield f.call()` and `yield f.tailcall()`.
+
+    Usage examples:
+
+    Tail call optimised recursion with tailcall():
+
+    @recur.stackless
+    def fact(n, acc=1):
+        if n == 0:
+            yield acc
+            return
+        yield fact.tailcall(n-1, n*acc)
+
+    Non-tail recursion with call() uses heap space so won't overflow:
+
+    @recur.stackless
+    def fib(n):
+        if n == 0:
+            yield 1
+            return
+        if n == 1:
+            yield 1
+            return
+        yield (yield fib.call(n-1)) + (yield fib.call(n-2))
+
+    Mutual recursion also works:
+
+    @recur.stackless
+    def is_odd(n):
+        if n == 0:
+            yield False
+            return
+        yield is_even.tailcall(n-1)
+
+    @recur.stackless
+    def is_even(n):
+        if n == 0:
+            yield True
+            return
+        yield is_odd.tailcall(n-1)
+
+    """
+
+    __slots__ = "func",
+
+    Thunk = namedtuple("Thunk", ("func", "args", "kwargs", "is_tailcall"))
+
+    def __init__(self, func):
+        self.func = func
+
+    def call(self, *args, **kwargs):
+        return self.Thunk(self.func, args, kwargs, False)
+
+    def tailcall(self, *args, **kwargs):
+        return self.Thunk(self.func, args, kwargs, True)
+
+    def __call__(self, *args, **kwargs):
+        s = [self.func(*args, **kwargs)]
+        r = []
+        v = None
+        while s:
+            try:
+                if r:
+                    v = s[-1].send(r[-1])
+                    r.pop()
+                else:
+                    v = next(s[-1])
+            except StopIteration:
+                s.pop()
+                continue
+
+            if isinstance(v, self.Thunk):
+                g = v.func(*v.args, **v.kwargs)
+                if v.is_tailcall:
+                    s[-1] = g
+                else:
+                    s.append(g)
+            else:
+                r.append(v)
+        return r[0] if r else None

fn/underscore.py

@@ -9,6 +9,7 @@
 from .op import apply, flip, identity
 from .uniform import map, zip
 
+
 div = operator.div if version_info[0] == 2 else operator.truediv
 
 letters = string.letters if version_info[0] == 2 else string.ascii_letters
@@ -189,4 +190,5 @@ def __call__(self, *args):
     __ror__ = fmap(flip(operator.or_), "other | self")
     __rxor__ = fmap(flip(operator.xor), "other ^ self")
 
+
 shortcut = _Callable()

tests/test_finger_tree.py

@@ -41,5 +41,6 @@ def test_iterator(self):
             sum(Deque.from_iterable(range(1, 20)))
         )
 
+
 if __name__ == '__main__':
     unittest.main()

tests/test_iterators.py

@@ -280,5 +280,5 @@ def test_accumulate(self):
         )
 
     def test_filterfalse(self):
-        l = iters.filterfalse(lambda x: x > 10, [1, 2, 3, 11, 12])
-        self.assertEqual([1, 2, 3], list(l))
+        filtered = iters.filterfalse(lambda x: x > 10, [1, 2, 3, 11, 12])
+        self.assertEqual([1, 2, 3], list(filtered))

tests/test_underscore.py

@@ -146,8 +146,7 @@ def test_comparator(self):
         self.assertFalse((_ == 10)(9))
 
     def test_none(self):
-        # FIXME: turning the '==' into 'is' throws an error
-        self.assertTrue((_ == None)(None))
+        self.assertTrue((_ == None)(None))  # noqa: E711
 
         class pushlist(list):
             def __lshift__(self, item):