moved lispy from 02 to 18

17-it-generator/aritprog_v3.py

@@ -5,7 +5,7 @@ import itertools
 def aritprog_gen(begin, step, end=None):
     first = type(begin + step)(begin)
     ap_gen = itertools.count(first, step)
-    if end is not None:
-        ap_gen = itertools.takewhile(lambda n: n < end, ap_gen)
-    return ap_gen
+    if end is None:
+        return ap_gen
+    return itertools.takewhile(lambda n: n < end, ap_gen)
 # end::ARITPROG_ITERTOOLS[]

17-it-generator/coroaverager.py

@@ -0,0 +1,43 @@
+"""
+A coroutine to compute a running average
+
+# tag::CORO_AVERAGER_TEST[]
+    >>> coro_avg = averager()  # <1>
+    >>> next(coro_avg)  # <2>
+    0.0
+    >>> coro_avg.send(10)  # <3>
+    10.0
+    >>> coro_avg.send(30)
+    20.0
+    >>> coro_avg.send(5)
+    15.0
+
+# end::CORO_AVERAGER_TEST[]
+# tag::CORO_AVERAGER_TEST_CONT[]
+
+    >>> coro_avg.send(20)  # <1>
+    16.25
+    >>> coro_avg.close()  # <2>
+    >>> coro_avg.close()  # <3>
+    >>> coro_avg.send(5)  # <4>
+    Traceback (most recent call last):
+      ...
+    StopIteration
+
+# end::CORO_AVERAGER_TEST_CONT[]
+
+"""
+
+# tag::CORO_AVERAGER[]
+from collections.abc import Generator
+
+def averager() -> Generator[float, float, None]:  # <1>
+    total = 0.0
+    count = 0
+    average = 0.0
+    while True:  # <2>
+        term = yield average  # <3>
+        total += term
+        count += 1
+        average = total/count
+# end::CORO_AVERAGER[]

17-it-generator/coroaverager2.py

@@ -0,0 +1,96 @@
+"""
+A coroutine to compute a running average.
+
+Testing ``averager2`` by itself::
+
+# tag::RETURNING_AVERAGER_DEMO_1[]
+
+    >>> coro_avg = averager2()
+    >>> next(coro_avg)
+    >>> coro_avg.send(10)  # <1>
+    >>> coro_avg.send(30)
+    >>> coro_avg.send(6.5)
+    >>> coro_avg.close()  # <2>
+
+# end::RETURNING_AVERAGER_DEMO_1[]
+
+Catching `StopIteration` to extract the value returned by
+the coroutine::
+
+# tag::RETURNING_AVERAGER_DEMO_2[]
+
+    >>> coro_avg = averager2()
+    >>> next(coro_avg)
+    >>> coro_avg.send(10)
+    >>> coro_avg.send(30)
+    >>> coro_avg.send(6.5)
+    >>> try:
+    ...     coro_avg.send(STOP)  # <1>
+    ... except StopIteration as exc:
+    ...     result = exc.value  # <2>
+    ...
+    >>> result  # <3>
+    Result(count=3, average=15.5)
+
+# end::RETURNING_AVERAGER_DEMO_2[]
+
+Using `yield from`:
+
+
+# tag::RETURNING_AVERAGER_DEMO_3[]
+
+    >>> def compute():
+    ...     res = yield from averager2(True)  # <1>
+    ...     print('computed:', res)  # <2>
+    ...     return res  # <3>
+    ...
+    >>> comp = compute()  # <4>
+    >>> for v in [None, 10, 20, 30, STOP]:  # <5>
+    ...     try:
+    ...         comp.send(v)  # <6>
+    ...     except StopIteration as exc:  # <7>
+    ...         result = exc.value
+    received: 10
+    received: 20
+    received: 30
+    received: <Sentinel>
+    computed: Result(count=3, average=20.0)
+    >>> result  # <8>
+    Result(count=3, average=20.0)
+
+# end::RETURNING_AVERAGER_DEMO_3[]
+"""
+
+# tag::RETURNING_AVERAGER_TOP[]
+from collections.abc import Generator
+from typing import Union, NamedTuple
+
+class Result(NamedTuple):  # <1>
+    count: int  # type: ignore  # <2>
+    average: float
+
+class Sentinel:  # <3>
+    def __repr__(self):
+        return f'<Sentinel>'
+
+STOP = Sentinel()  # <4>
+
+SendType = Union[float, Sentinel]  # <5>
+# end::RETURNING_AVERAGER_TOP[]
+# tag::RETURNING_AVERAGER[]
+def averager2(verbose: bool = False) -> Generator[None, SendType, Result]:  # <1>
+    total = 0.0
+    count = 0
+    average = 0.0
+    while True:
+        term = yield  # <2>
+        if verbose:
+            print('received:', term)
+        if isinstance(term, Sentinel):  # <3>
+            break
+        total += term  # <4>
+        count += 1
+        average = total / count
+    return Result(count, average)  # <5>
+
+# end::RETURNING_AVERAGER[]

17-it-generator/fibo_gen.py

@@ -0,0 +1,7 @@
+from collections.abc import Iterator
+
+def fibonacci() -> Iterator[int]:
+    a, b = 0, 1
+    while True:
+        yield a
+        a, b = b, a + b

17-it-generator/sentence_gen.py

@@ -21,7 +21,7 @@ class Sentence:
     def __iter__(self):
         for word in self.words:  # <1>
             yield word  # <2>
-        return  # <3>
+        # <3>
 
 # done! <4>