refactor FlatMapValues and StarFlatMap

docs/reference.md

@@ -144,6 +144,9 @@ Same as `FilterKeys` but for `v` in `(k, v)` pairs
 >>> [range(0, 5), range(100, 105)] | FlatMap(lambda it: (x for x in it if x % 2 == 0)) | Pipe(list)
 [0, 2, 4, 100, 102, 104]
 
+>>> [range(0, 5), range(100, 105)] | FlatMap(lambda it: it | Filter(lambda x: x % 2 == 0)) | Pipe(list)
+[0, 2, 4, 100, 102, 104]
+
 ```
 
 ## FlatMapValues
@@ -152,8 +155,7 @@ Same as `FilterKeys` but for `v` in `(k, v)` pairs
 >>> [("a", ["x", "y", "z"]), ("b", ["p", "r"])] | FlatMapValues(lambda x: x) | Pipe(list)
 [('a', 'x'), ('a', 'y'), ('a', 'z'), ('b', 'p'), ('b', 'r')]
 
->>> keep_even = lambda it: it | Filter(lambda x: x % 2 == 0)
->>> [('a', [0, 1, 2]), ('b', [3, 4])] | FlatMapValues(keep_even) | Pipe(list)
+>>> [('a', [0, 1, 2]), ('b', [3, 4])] | FlatMapValues(yield_even) | Pipe(list)
 [('a', 0), ('a', 2), ('b', 4)]
 
 ```

pipe21.py

@@ -23,7 +23,7 @@ class FilterFalse  (B): __ror__ = lambda self, it: itertools.filterfalse(self.f,
 class FilterKeys   (B): __ror__ = lambda self, it: (kv for kv in it if (self.f or bool)(kv[0]))
 class FilterValues (B): __ror__ = lambda self, it: (kv for kv in it if (self.f or bool)(kv[1]))
 class FlatMap      (B): __ror__ = lambda self, it: itertools.chain.from_iterable(self.f(x) for x in it)
-class FlatMapValues(B): __ror__ = lambda self, it: it | FlatMap(lambda kv: ((kv[0], x) for x in self.f(kv[1])))
+class FlatMapValues(B): __ror__ = lambda self, it: ((k, v) for k, vs in it for v in self.f(vs))
 class KeyBy        (B): __ror__ = lambda self, it: ((self.f(x), x) for x in it)
 class ValueBy      (B): __ror__ = lambda self, it: ((x, self.f(x)) for x in it)
 class Append       (B): __ror__ = lambda self, it: ((*x, self.f(x)) for x in it)
@@ -41,7 +41,7 @@ class ReduceByKey  (B): __ror__ = lambda self, it: it | GroupBy(lambda kv: kv[0]
 class Apply        (B): __ror__ = lambda self, x: x | Exec(self.f, x)
 class StarPipe     (B): __ror__ = lambda self, x: self.f(*x)
 class StarMap      (B): __ror__ = lambda self, x: itertools.starmap(self.f, x)
-class StarFlatMap  (B): __ror__ = lambda self, x: itertools.chain.from_iterable(itertools.starmap(self.f, x))
+class StarFlatMap  (B): __ror__ = lambda self, x: itertools.starmap(self.f, x) | Pipe(itertools.chain.from_iterable)
 class MapApply     (B): __ror__ = lambda self, it: (x | Apply(self.f) for x in it)
 class Switch       (B): __ror__ = lambda self, x: next((v(x) for k, v in self.f if k(x)), x)
 class MapSwitch    (B): __ror__ = lambda self, it: (x | Switch(self.f) for x in it)