complete draft: update from Atlas

13-protocol-abc/lotto.py

@@ -5,7 +5,7 @@ import random
 from tombola import Tombola
 
 
-class LotteryBlower(Tombola):
+class LottoBlower(Tombola):
 
     def __init__(self, iterable):
         self._balls = list(iterable)  # <1>
@@ -17,14 +17,14 @@ class LotteryBlower(Tombola):
         try:
             position = random.randrange(len(self._balls))  # <2>
         except ValueError:
-            raise LookupError('pick from empty BingoCage')
+            raise LookupError('pick from empty LottoBlower')
         return self._balls.pop(position)  # <3>
 
     def loaded(self):  # <4>
         return bool(self._balls)
 
     def inspect(self):  # <5>
-        return tuple(sorted(self._balls))
+        return tuple(self._balls)
 
 
 # end::LOTTERY_BLOWER[]

13-protocol-abc/tombola.py

@@ -28,7 +28,7 @@ class Tombola(abc.ABC):  # <1>
             except LookupError:
                 break
         self.load(items)  # <7>
-        return tuple(sorted(items))
+        return tuple(items)
 
 
 # end::TOMBOLA_ABC[]

13-protocol-abc/tombola_runner.py

@@ -1,4 +1,5 @@
-# tag::TOMBOLA_RUNNER[]
+#!/usr/bin/env python3
+
 import doctest
 
 from tombola import Tombola
@@ -13,8 +14,7 @@ TEST_MSG = '{0:16} {1.attempted:2} tests, {1.failed:2} failed - {2}'
 def main(argv):
     verbose = '-v' in argv
     real_subclasses = Tombola.__subclasses__()  # <2>
-    virtual_subclasses = list(Tombola._abc_registry)  # <3>
-
+    virtual_subclasses = [tombolist.TomboList]  # <3>
     for cls in real_subclasses + virtual_subclasses:  # <4>
         test(cls, verbose)
 
@@ -33,4 +33,3 @@ def test(cls, verbose=False):
 if __name__ == '__main__':
     import sys
     main(sys.argv)
-# end::TOMBOLA_RUNNER[]

13-protocol-abc/tombola_tests.rst

@@ -11,8 +11,8 @@ Create and load instance from iterable::
     >>> globe = ConcreteTombola(balls)
     >>> globe.loaded()
     True
-    >>> globe.inspect()
-    (0, 1, 2)
+    >>> sorted(globe.inspect())
+    [0, 1, 2]
 
 
 Pick and collect balls::

13-protocol-abc/tombolist.py

@@ -18,6 +18,6 @@ class TomboList(list):  # <2>
         return bool(self)  # <6>
 
     def inspect(self):
-        return tuple(sorted(self))
+        return tuple(self)
 
 # Tombola.register(TomboList)  # <7>

15-more-types/cafeteria/contravariant.py

@@ -38,8 +38,7 @@ deploy(trash_can)
 # tag::DEPLOY_NOT_VALID[]
 compost_can: TrashCan[Compostable] = TrashCan()
 deploy(compost_can)
-# end::DEPLOY_NOT_VALID[]
-
-## Argument 1 to "deploy" has
+## mypy: Argument 1 to "deploy" has
 ## incompatible type "TrashCan[Compostable]"
 ##          expected "TrashCan[Biodegradable]"
+# end::DEPLOY_NOT_VALID[]

15-more-types/cafeteria/covariant.py

@@ -38,11 +38,12 @@ orange_juice_dispenser = BeverageDispenser(OrangeJuice())
 install(orange_juice_dispenser)
 # end::INSTALL_JUICE_DISPENSERS[]
 
-################################################ not a juice dispenser
+################################################ more general dispenser
 
+# tag::INSTALL_BEVERAGE_DISPENSER[]
 beverage_dispenser = BeverageDispenser(Beverage())
-
-## Argument 1 to "install" has
+install(beverage_dispenser)
+## mypy: Argument 1 to "install" has
 ## incompatible type "BeverageDispenser[Beverage]"
 ##          expected "BeverageDispenser[Juice]"
-install(beverage_dispenser)
+# end::INSTALL_BEVERAGE_DISPENSER[]

15-more-types/cafeteria/invariant.py

@@ -37,7 +37,7 @@ install(juice_dispenser)
 # tag::INSTALL_BEVERAGE_DISPENSER[]
 beverage_dispenser = BeverageDispenser(Beverage())
 install(beverage_dispenser)
-## Argument 1 to "install" has
+## mypy: Argument 1 to "install" has
 ## incompatible type "BeverageDispenser[Beverage]"
 ##          expected "BeverageDispenser[Juice]"
 # end::INSTALL_BEVERAGE_DISPENSER[]
@@ -48,7 +48,7 @@ install(beverage_dispenser)
 # tag::INSTALL_ORANGE_JUICE_DISPENSER[]
 orange_juice_dispenser = BeverageDispenser(OrangeJuice())
 install(orange_juice_dispenser)
-# end::INSTALL_ORANGE_JUICE_DISPENSER[]
-## Argument 1 to "install" has
+## mypy: Argument 1 to "install" has
 ## incompatible type "BeverageDispenser[OrangeJuice]"
 ##          expected "BeverageDispenser[Juice]"
+# end::INSTALL_ORANGE_JUICE_DISPENSER[]

15-more-types/cast/empty.py

@@ -0,0 +1,2 @@
+# Mypy 0.812 can't spot this inevitable runtime IndexError
+print([][0])

15-more-types/cast/find.py

@@ -0,0 +1,23 @@
+# tag::CAST[]
+from typing import cast
+
+def find_first_str(a: list[object]) -> str:
+    index = next(i for i, x in enumerate(a) if isinstance(x, str))
+    # We only get here if there's at least one string in a
+    return cast(str, a[index])
+# end::CAST[]
+
+
+from typing import TYPE_CHECKING
+
+l1 = [10, 20, 'thirty', 40]
+if TYPE_CHECKING:
+    reveal_type(l1)
+
+print(find_first_str(l1))
+
+l2 = [0, ()]
+try:
+    find_first_str(l2)
+except StopIteration as e:
+    print(repr(e))

15-more-types/cast/tcp_echo.py

@@ -0,0 +1,37 @@
+import asyncio
+
+from asyncio import StreamReader, StreamWriter
+
+# tag::CAST_IMPORTS[]
+from asyncio.trsock import TransportSocket
+from typing import cast
+# end::CAST_IMPORTS[]
+
+async def handle_echo(reader: StreamReader, writer: StreamWriter) -> None:
+    data = await reader.read(100)
+    message = data.decode()
+    addr = writer.get_extra_info('peername')
+
+    print(f"Received {message!r} from {addr!r}")
+
+    print(f"Send: {message!r}")
+    writer.write(data)
+    await writer.drain()
+
+    print("Close the connection")
+    writer.close()
+
+async def main() -> None:
+    server = await asyncio.start_server(
+        handle_echo, '127.0.0.1', 8888)
+
+    # tag::CAST_USE[]
+    socket_list = cast(tuple[TransportSocket, ...], server.sockets)
+    addr = socket_list[0].getsockname()
+    # end::CAST_USE[]
+    print(f'Serving on {addr}')
+
+    async with server:
+        await server.serve_forever()
+
+asyncio.run(main())

15-more-types/cast/tcp_echo_no_cast.py

@@ -0,0 +1,29 @@
+import asyncio
+
+from asyncio import StreamReader, StreamWriter
+
+async def handle_echo(reader: StreamReader, writer: StreamWriter) -> None:
+    data = await reader.read(100)
+    message = data.decode()
+    addr = writer.get_extra_info('peername')
+
+    print(f"Received {message!r} from {addr!r}")
+
+    print(f"Send: {message!r}")
+    writer.write(data)
+    await writer.drain()
+
+    print("Close the connection")
+    writer.close()
+
+async def main() -> None:
+    server = await asyncio.start_server(
+        handle_echo, '127.0.0.1', 8888)
+
+    addr = server.sockets[0].getsockname()
+    print(f'Serving on {addr}')
+
+    async with server:
+        await server.serve_forever()
+
+asyncio.run(main())

15-more-types/clip_annot_demo.py

@@ -0,0 +1,3 @@
+from clip_annot_post import clip
+
+print(clip.__annotations__)

15-more-types/clip_annot_post.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 """
     >>> clip('banana ', 6)
     'banana'
@@ -18,9 +20,9 @@
 """
 
 # tag::CLIP_ANNOT[]
-
-def clip(text: str, max_len: 'int > 0' = 80) -> str:  # <1>
-    """Return text clipped at the last space before or after max_len
+def clip(text: str, max_len: int = 80) -> str:
+    """Return new ``str`` clipped at last space before or after ``max_len``.
+       Return full ``text`` if no space found.
     """
     end = None
     if len(text) > max_len:
@@ -31,7 +33,7 @@ def clip(text: str, max_len: 'int > 0' = 80) -> str:  # <1>
             space_after = text.rfind(' ', max_len)
             if space_after >= 0:
                 end = space_after
-    if end is None:  # no spaces were found
+    if end is None:
         end = len(text)
     return text[:end].rstrip()
 

15-more-types/clip_annot_signature.rst

@@ -1,10 +0,0 @@
->>> from clip_annot import clip
->>> from inspect import signature
->>> sig = signature(clip)
->>> sig.return_annotation
-<class 'str'>
->>> for param in sig.parameters.values():
-...     note = repr(param.annotation).ljust(13)
-...     print(note, ':', param.name, '=', param.default)
-<class 'str'> : text = <class 'inspect._empty'>
-'int > 0'     : max_len = 80

15-more-types/lotto/generic_lotto.py

@@ -0,0 +1,29 @@
+import random
+
+from collections.abc import Iterable
+from typing import TypeVar, Generic
+
+from tombola import Tombola
+
+T = TypeVar('T')
+
+class LottoBlower(Tombola, Generic[T]):  # <1>
+
+    def __init__(self, items: Iterable[T]) -> None:  # <2>
+        self._balls = list[T](items)
+
+    def load(self, items: Iterable[T]) -> None:  # <3>
+        self._balls.extend(items)
+
+    def pick(self) -> T:  # <4>
+        try:
+            position = random.randrange(len(self._balls))
+        except ValueError:
+            raise LookupError('pick from empty LottoBlower')
+        return self._balls.pop(position)
+
+    def loaded(self) -> bool:  # <5>
+        return bool(self._balls)
+
+    def inspect(self) -> tuple[T, ...]:  # <6>
+        return tuple(self._balls)

15-more-types/lotto/generic_lotto_demo.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python3
+
+from typing import TYPE_CHECKING
+
+# tag::LOTTO_USE[]
+from generic_lotto import LottoBlower
+
+machine = LottoBlower[int](range(1, 11))  # <1>
+
+first = machine.pick()  # <2>
+remain = machine.inspect()  # <3>
+# end::LOTTO_USE[]
+
+expected = set(i for i in range(1, 11) if i != first)
+
+assert set(remain) == expected
+
+print('picked:', first)
+print('remain:', remain)
+
+if TYPE_CHECKING:
+    reveal_type(first)
+    # Revealed type is 'builtins.int*'
+if TYPE_CHECKING:
+    reveal_type(remain)
+    # Revealed type is 'builtins.tuple[builtins.int*]'
+
+

15-more-types/lotto/generic_lotto_errors.py

@@ -0,0 +1,18 @@
+from generic_lotto import LottoBlower
+
+machine = LottoBlower[int]([1, .2])
+## error: List item 1 has incompatible type "float";  # <1>
+##        expected "int"
+
+machine = LottoBlower[int](range(1, 11))
+
+machine.load('ABC')
+## error: Argument 1 to "load" of "LottoBlower"  # <2>
+##        has incompatible type "str";
+##        expected "Iterable[int]"
+## note:  Following member(s) of "str" have conflicts:
+## note:      Expected:
+## note:          def __iter__(self) -> Iterator[int]
+## note:      Got:
+## note:          def __iter__(self) -> Iterator[str]
+

15-more-types/lotto/tombola.py

@@ -0,0 +1,34 @@
+# tag::TOMBOLA_ABC[]
+
+import abc
+
+class Tombola(abc.ABC):  # <1>
+
+    @abc.abstractmethod
+    def load(self, iterable):  # <2>
+        """Add items from an iterable."""
+
+    @abc.abstractmethod
+    def pick(self):  # <3>
+        """Remove item at random, returning it.
+
+        This method should raise `LookupError` when the instance is empty.
+        """
+
+    def loaded(self):  # <4>
+        """Return `True` if there's at least 1 item, `False` otherwise."""
+        return bool(self.inspect())  # <5>
+
+    def inspect(self):
+        """Return a sorted tuple with the items currently inside."""
+        items = []
+        while True:  # <6>
+            try:
+                items.append(self.pick())
+            except LookupError:
+                break
+        self.load(items)  # <7>
+        return tuple(items)
+
+
+# end::TOMBOLA_ABC[]

15-more-types/mysum.py

@@ -1,13 +1,14 @@
-from functools import reduce  # <1>
-from operator import add
-from typing import overload, Iterable, Union, TypeVar
+import functools
+import operator
+from collections.abc import Iterable
+from typing import overload, Union, TypeVar
 
 T = TypeVar('T')
-S = TypeVar('S')  # <2>
+S = TypeVar('S')  # <1>
 
 @overload
-def sum(it: Iterable[T]) -> Union[T, int]: ...  # <3>
+def sum(it: Iterable[T]) -> Union[T, int]: ...  # <2>
 @overload
-def sum(it: Iterable[T], /, start: S) -> Union[T, S]: ...  # <4>
-def sum(it, /, start=0):  # <5>
-    return reduce(add, it, start)
+def sum(it: Iterable[T], /, start: S) -> Union[T, S]: ...  # <3>
+def sum(it, /, start=0):  # <4>
+    return functools.reduce(operator.add, it, start)

15-more-types/protocol/abs_demo.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+
+import math
+from typing import NamedTuple, SupportsAbs
+
+class Vector2d(NamedTuple):
+    x: float
+    y: float
+
+    def __abs__(self) -> float:  # <1>
+        return math.hypot(self.x, self.y)
+
+def is_unit(v: SupportsAbs[float]) -> bool:  # <2>
+    """'True' if the magnitude of 'v' is close to 1."""
+    return math.isclose(abs(v), 1.0)  # <3>
+
+assert issubclass(Vector2d, SupportsAbs)  # <4>
+
+v0 = Vector2d(0, 1)  # <5>
+sqrt2 = math.sqrt(2)
+v1 = Vector2d(sqrt2 / 2, sqrt2 / 2)
+v2 = Vector2d(1, 1)
+v3 = complex(.5, math.sqrt(3) / 2)
+v4 = 1  # <6>
+
+assert is_unit(v0)
+assert is_unit(v1)
+assert not is_unit(v2)
+assert is_unit(v3)
+assert is_unit(v4)
+
+print('OK')

15-more-types/protocol/mymax/mymax.py

@@ -12,10 +12,10 @@ MISSING = object()
 EMPTY_MSG = 'max() arg is an empty sequence'
 
 @overload
-def max(__arg1: LT, __arg2: LT, *_args: LT, key: None = ...) -> LT:
+def max(__arg1: LT, __arg2: LT, *args: LT, key: None = ...) -> LT:
     ...
 @overload
-def max(__arg1: T, __arg2: T, *_args: T, key: Callable[[T], LT]) -> T:
+def max(__arg1: T, __arg2: T, *args: T, key: Callable[[T], LT]) -> T:
     ...
 @overload
 def max(__iterable: Iterable[LT], *, key: None = ...) -> LT:

15-more-types/protocol/random/generic_randompick.py

@@ -0,0 +1,7 @@
+from typing import Protocol, runtime_checkable, TypeVar
+
+T_co = TypeVar('T_co', covariant=True)  # <1>
+
+@runtime_checkable
+class RandomPicker(Protocol[T_co]):  # <2>
+    def pick(self) -> T_co: ...  # <3>

15-more-types/protocol/random/generic_randompick_test.py

@@ -1,24 +1,26 @@
 import random
-from typing import Iterable, TYPE_CHECKING
+from typing import Iterable, Generic, TypeVar, TYPE_CHECKING
 
-from randompick_generic import GenericRandomPicker
+T_co = TypeVar('T_co', covariant=True)
+
+from generic_randompick import RandomPicker
 
 
-class LottoPicker:
-    def __init__(self, items: Iterable[int]) -> None:
+class LottoPicker(Generic[T_co]):
+    def __init__(self, items: Iterable[T_co]) -> None:
         self._items = list(items)
         random.shuffle(self._items)
 
-    def pick(self) -> int:
+    def pick(self) -> T_co:
         return self._items.pop()
 
 
 def test_issubclass() -> None:
-    assert issubclass(LottoPicker, GenericRandomPicker)
+    assert issubclass(LottoPicker, RandomPicker)
 
 
 def test_isinstance() -> None:
-    popper: GenericRandomPicker = LottoPicker([1])
+    popper: RandomPicker = LottoPicker[int]([1])
     if TYPE_CHECKING:
         reveal_type(popper)
         # Revealed type is '???'

15-more-types/randompick_generic.py

@@ -1,7 +0,0 @@
-from typing import Protocol, runtime_checkable, TypeVar
-
-T_co = TypeVar('T_co', covariant=True)
-
-@runtime_checkable
-class GenericRandomPicker(Protocol[T_co]):
-    def pick(self) -> T_co: ...

18-context-mngr/lispy/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2010-2017 Peter Norvig
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

18-context-mngr/lispy/README.md

@@ -0,0 +1,24 @@
+# lis.py
+
+This directory contains 3 versions of
+[Peter Norvig's `lis.py` interpreter](https://norvig.com/lispy.html)
+for Scheme.
+
+* `original/`: Norvig's `lis.py` unchanged, `lispy.py` with
+[minor changes](https://github.com/norvig/pytudes/pull/106) to run on Python 3,
+and the `lispytest.py` custom test suite;
+* `py3.9/`: `lis.py` with type hints and a few minor edits—requires Python 3.9;
+* `py3.10/`: `lis.py` with type hints, pattern matching, and minor edits—requires Python 3.10.
+
+The `py3.9/` and `py3.10/` directories also have identical `lis_test.py` to run with
+[pytest](https://docs.pytest.org).
+These files include all the
+[`lis_tests` suite](https://github.com/norvig/pytudes/blob/60168bce8cdfacf57c92a5b2979f0b2e95367753/py/lispytest.py#L5)
+from `original/lispytest.py`,
+and individual tests for each expression and special form handled by `evaluate`.
+
+## Provenance, Copyright and License
+
+`lis.py` is published in the [norvig/pytudes](https://github.com/norvig/pytudes) repository on Github.
+The copyright holder is Peter Norvig and the code is licensed under the
+[MIT license](https://github.com/norvig/pytudes/blob/60168bce8cdfacf57c92a5b2979f0b2e95367753/LICENSE).

18-context-mngr/lispy/original/lis.py

@@ -0,0 +1,132 @@
+################ Lispy: Scheme Interpreter in Python 3.3+
+
+## (c) Peter Norvig, 2010-18; See http://norvig.com/lispy.html
+
+################ Imports and Types
+
+import math
+import operator as op
+from collections import ChainMap as Environment
+
+Symbol = str          # A Lisp Symbol is implemented as a Python str
+List   = list         # A Lisp List   is implemented as a Python list
+Number = (int, float) # A Lisp Number is implemented as a Python int or float
+
+class Procedure(object):
+    "A user-defined Scheme procedure."
+    def __init__(self, parms, body, env):
+        self.parms, self.body, self.env = parms, body, env
+    def __call__(self, *args):
+        env =  Environment(dict(zip(self.parms, args)), self.env)
+        return eval(self.body, env)
+
+################ Global Environment
+
+def standard_env():
+    "An environment with some Scheme standard procedures."
+    env = {}
+    env.update(vars(math)) # sin, cos, sqrt, pi, ...
+    env.update({
+        '+':op.add, '-':op.sub, '*':op.mul, '/':op.truediv, 
+        '>':op.gt, '<':op.lt, '>=':op.ge, '<=':op.le, '=':op.eq, 
+        'abs':     abs,
+        'append':  op.add,  
+        'apply':   lambda proc, args: proc(*args),
+        'begin':   lambda *x: x[-1],
+        'car':     lambda x: x[0],
+        'cdr':     lambda x: x[1:], 
+        'cons':    lambda x,y: [x] + y,
+        'eq?':     op.is_, 
+        'equal?':  op.eq, 
+        'length':  len, 
+        'list':    lambda *x: list(x), 
+        'list?':   lambda x: isinstance(x,list), 
+        'map':     lambda *args: list(map(*args)),
+        'max':     max,
+        'min':     min,
+        'not':     op.not_,
+        'null?':   lambda x: x == [], 
+        'number?': lambda x: isinstance(x, Number),   
+        'procedure?': callable,
+        'round':   round,
+        'symbol?': lambda x: isinstance(x, Symbol),
+    })
+    return env
+
+global_env = standard_env()
+
+################ Parsing: parse, tokenize, and read_from_tokens
+
+def parse(program):
+    "Read a Scheme expression from a string."
+    return read_from_tokens(tokenize(program))
+
+def tokenize(s):
+    "Convert a string into a list of tokens."
+    return s.replace('(',' ( ').replace(')',' ) ').split()
+
+def read_from_tokens(tokens):
+    "Read an expression from a sequence of tokens."
+    if len(tokens) == 0:
+        raise SyntaxError('unexpected EOF while reading')
+    token = tokens.pop(0)
+    if '(' == token:
+        L = []
+        while tokens[0] != ')':
+            L.append(read_from_tokens(tokens))
+        tokens.pop(0) # pop off ')'
+        return L
+    elif ')' == token:
+        raise SyntaxError('unexpected )')
+    else:
+        return atom(token)
+
+def atom(token):
+    "Numbers become numbers; every other token is a symbol."
+    try: return int(token)
+    except ValueError:
+        try: return float(token)
+        except ValueError:
+            return Symbol(token)
+
+################ Interaction: A REPL
+
+def repl(prompt='lis.py> '):
+    "A prompt-read-eval-print loop."
+    while True:
+        val = eval(parse(input(prompt)))
+        if val is not None:
+            print(lispstr(val))
+
+def lispstr(exp):
+    "Convert a Python object back into a Lisp-readable string."
+    if isinstance(exp, List):
+        return '(' + ' '.join(map(lispstr, exp)) + ')' 
+    else:
+        return str(exp)
+
+################ eval
+
+def eval(x, env=global_env):
+    "Evaluate an expression in an environment."
+    if isinstance(x, Symbol):      # variable reference
+        return env[x]
+    elif not isinstance(x, List):  # constant literal
+        return x                
+    elif x[0] == 'quote':          # (quote exp)
+        (_, exp) = x
+        return exp
+    elif x[0] == 'if':             # (if test conseq alt)
+        (_, test, conseq, alt) = x
+        exp = (conseq if eval(test, env) else alt)
+        return eval(exp, env)
+    elif x[0] == 'define':         # (define var exp)
+        (_, var, exp) = x
+        env[var] = eval(exp, env)
+    elif x[0] == 'lambda':         # (lambda (var...) body)
+        (_, parms, body) = x
+        return Procedure(parms, body, env)
+    else:                          # (proc arg...)
+        proc = eval(x[0], env)
+        args = [eval(exp, env) for exp in x[1:]]
+        return proc(*args)

18-context-mngr/lispy/original/lispy.py

@@ -0,0 +1,316 @@
+################ Scheme Interpreter in Python
+
+## (c) Peter Norvig, 2010; See http://norvig.com/lispy2.html
+
+################ Symbol, Procedure, classes
+
+import re, sys, io
+
+class Symbol(str): pass
+
+def Sym(s, symbol_table={}):
+    "Find or create unique Symbol entry for str s in symbol table."
+    if s not in symbol_table: symbol_table[s] = Symbol(s)
+    return symbol_table[s]
+
+_quote, _if, _set, _define, _lambda, _begin, _definemacro, = map(Sym,
+"quote   if   set!  define   lambda   begin   define-macro".split())
+
+_quasiquote, _unquote, _unquotesplicing = map(Sym,
+"quasiquote   unquote   unquote-splicing".split())
+
+class Procedure:
+    "A user-defined Scheme procedure."
+    def __init__(self, parms, exp, env):
+        self.parms, self.exp, self.env = parms, exp, env
+    def __call__(self, *args):
+        return eval(self.exp, Env(self.parms, args, self.env))
+
+################ parse, read, and user interaction
+
+def parse(inport):
+    "Parse a program: read and expand/error-check it."
+    # Backwards compatibility: given a str, convert it to an InPort
+    if isinstance(inport, str): inport = InPort(io.StringIO(inport))
+    return expand(read(inport), toplevel=True)
+
+eof_object = Symbol('#<eof-object>') # Note: uninterned; can't be read
+
+class InPort:
+    "An input port. Retains a line of chars."
+    tokenizer = r"""\s*(,@|[('`,)]|"(?:[\\].|[^\\"])*"|;.*|[^\s('"`,;)]*)(.*)"""
+    def __init__(self, file):
+        self.file = file; self.line = ''
+    def next_token(self):
+        "Return the next token, reading new text into line buffer if needed."
+        while True:
+            if self.line == '': self.line = self.file.readline()
+            if self.line == '': return eof_object
+            token, self.line = re.match(InPort.tokenizer, self.line).groups()
+            if token != '' and not token.startswith(';'):
+                return token
+
+def readchar(inport):
+    "Read the next character from an input port."
+    if inport.line != '':
+        ch, inport.line = inport.line[0], inport.line[1:]
+        return ch
+    else:
+        return inport.file.read(1) or eof_object
+
+def read(inport):
+    "Read a Scheme expression from an input port."
+    def read_ahead(token):
+        if '(' == token:
+            L = []
+            while True:
+                token = inport.next_token()
+                if token == ')': return L
+                else: L.append(read_ahead(token))
+        elif ')' == token: raise SyntaxError('unexpected )')
+        elif token in quotes: return [quotes[token], read(inport)]
+        elif token is eof_object: raise SyntaxError('unexpected EOF in list')
+        else: return atom(token)
+    # body of read:
+    token1 = inport.next_token()
+    return eof_object if token1 is eof_object else read_ahead(token1)
+
+quotes = {"'":_quote, "`":_quasiquote, ",":_unquote, ",@":_unquotesplicing}
+
+def atom(token):
+    'Numbers become numbers; #t and #f are booleans; "..." string; otherwise Symbol.'
+    if token == '#t': return True
+    elif token == '#f': return False
+    elif token[0] == '"': return token[1:-1]
+    try: return int(token)
+    except ValueError:
+        try: return float(token)
+        except ValueError:
+            try: return complex(token.replace('i', 'j', 1))
+            except ValueError:
+                return Sym(token)
+
+def to_string(x):
+    "Convert a Python object back into a Lisp-readable string."
+    if x is True: return "#t"
+    elif x is False: return "#f"
+    elif isa(x, Symbol): return x
+    elif isa(x, str): return repr(x)
+    elif isa(x, list): return '('+' '.join(map(to_string, x))+')'
+    elif isa(x, complex): return str(x).replace('j', 'i')
+    else: return str(x)
+
+def load(filename):
+    "Eval every expression from a file."
+    repl(None, InPort(open(filename)), None)
+
+def repl(prompt='lispy> ', inport=InPort(sys.stdin), out=sys.stdout):
+    "A prompt-read-eval-print loop."
+    sys.stderr.write("Lispy version 2.0\n")
+    while True:
+        try:
+            if prompt: sys.stderr.write(prompt)
+            x = parse(inport)
+            if x is eof_object: return
+            val = eval(x)
+            if val is not None and out: print(to_string(val), file=out)
+        except Exception as e:
+            print('%s: %s' % (type(e).__name__, e))
+
+################ Environment class
+
+class Env(dict):
+    "An environment: a dict of {'var':val} pairs, with an outer Env."
+    def __init__(self, parms=(), args=(), outer=None):
+        # Bind parm list to corresponding args, or single parm to list of args
+        self.outer = outer
+        if isa(parms, Symbol):
+            self.update({parms:list(args)})
+        else:
+            if len(args) != len(parms):
+                raise TypeError('expected %s, given %s, '
+                                % (to_string(parms), to_string(args)))
+            self.update(zip(parms,args))
+    def find(self, var):
+        "Find the innermost Env where var appears."
+        if var in self: return self
+        elif self.outer is None: raise LookupError(var)
+        else: return self.outer.find(var)
+
+def is_pair(x): return x != [] and isa(x, list)
+def cons(x, y): return [x]+y
+
+def callcc(proc):
+    "Call proc with current continuation; escape only"
+    ball = RuntimeWarning("Sorry, can't continue this continuation any longer.")
+    def throw(retval): ball.retval = retval; raise ball
+    try:
+        return proc(throw)
+    except RuntimeWarning as w:
+        if w is ball: return ball.retval
+        else: raise w
+
+def add_globals(self):
+    "Add some Scheme standard procedures."
+    import math, cmath, operator as op
+    self.update(vars(math))
+    self.update(vars(cmath))
+    self.update({
+     '+':op.add, '-':op.sub, '*':op.mul, '/':op.truediv, 'not':op.not_,
+     '>':op.gt, '<':op.lt, '>=':op.ge, '<=':op.le, '=':op.eq,
+     'equal?':op.eq, 'eq?':op.is_, 'length':len, 'cons':cons,
+     'car':lambda x:x[0], 'cdr':lambda x:x[1:], 'append':op.add,
+     'list':lambda *x:list(x), 'list?': lambda x:isa(x,list),
+     'null?':lambda x:x==[], 'symbol?':lambda x: isa(x, Symbol),
+     'boolean?':lambda x: isa(x, bool), 'pair?':is_pair,
+     'port?': lambda x:isa(x,file), 'apply':lambda proc,l: proc(*l),
+     'eval':lambda x: eval(expand(x)), 'load':lambda fn: load(fn), 'call/cc':callcc,
+     'open-input-file':open,'close-input-port':lambda p: p.file.close(),
+     'open-output-file':lambda f:open(f,'w'), 'close-output-port':lambda p: p.close(),
+     'eof-object?':lambda x:x is eof_object, 'read-char':readchar,
+     'read':read, 'write':lambda x,port=sys.stdout:port.write(to_string(x)),
+     'display':lambda x,port=sys.stdout:port.write(x if isa(x,str) else to_string(x))})
+    return self
+
+isa = isinstance
+
+global_env = add_globals(Env())
+
+################ eval (tail recursive)
+
+def eval(x, env=global_env):
+    "Evaluate an expression in an environment."
+    while True:
+        if isa(x, Symbol):       # variable reference
+            return env.find(x)[x]
+        elif not isa(x, list):   # constant literal
+            return x
+        elif x[0] is _quote:     # (quote exp)
+            (_, exp) = x
+            return exp
+        elif x[0] is _if:        # (if test conseq alt)
+            (_, test, conseq, alt) = x
+            x = (conseq if eval(test, env) else alt)
+        elif x[0] is _set:       # (set! var exp)
+            (_, var, exp) = x
+            env.find(var)[var] = eval(exp, env)
+            return None
+        elif x[0] is _define:    # (define var exp)
+            (_, var, exp) = x
+            env[var] = eval(exp, env)
+            return None
+        elif x[0] is _lambda:    # (lambda (var*) exp)
+            (_, vars, exp) = x
+            return Procedure(vars, exp, env)
+        elif x[0] is _begin:     # (begin exp+)
+            for exp in x[1:-1]:
+                eval(exp, env)
+            x = x[-1]
+        else:                    # (proc exp*)
+            exps = [eval(exp, env) for exp in x]
+            proc = exps.pop(0)
+            if isa(proc, Procedure):
+                x = proc.exp
+                env = Env(proc.parms, exps, proc.env)
+            else:
+                return proc(*exps)
+
+################ expand
+
+def expand(x, toplevel=False):
+    "Walk tree of x, making optimizations/fixes, and signaling SyntaxError."
+    require(x, x!=[])                    # () => Error
+    if not isa(x, list):                 # constant => unchanged
+        return x
+    elif x[0] is _quote:                 # (quote exp)
+        require(x, len(x)==2)
+        return x
+    elif x[0] is _if:
+        if len(x)==3: x = x + [None]     # (if t c) => (if t c None)
+        require(x, len(x)==4)
+        return list(map(expand, x))
+    elif x[0] is _set:
+        require(x, len(x)==3);
+        var = x[1]                       # (set! non-var exp) => Error
+        require(x, isa(var, Symbol), "can set! only a symbol")
+        return [_set, var, expand(x[2])]
+    elif x[0] is _define or x[0] is _definemacro:
+        require(x, len(x)>=3)
+        _def, v, body = x[0], x[1], x[2:]
+        if isa(v, list) and v:           # (define (f args) body)
+            f, args = v[0], v[1:]        #  => (define f (lambda (args) body))
+            return expand([_def, f, [_lambda, args]+body])
+        else:
+            require(x, len(x)==3)        # (define non-var/list exp) => Error
+            require(x, isa(v, Symbol), "can define only a symbol")
+            exp = expand(x[2])
+            if _def is _definemacro:
+                require(x, toplevel, "define-macro only allowed at top level")
+                proc = eval(exp)
+                require(x, callable(proc), "macro must be a procedure")
+                macro_table[v] = proc    # (define-macro v proc)
+                return None              #  => None; add v:proc to macro_table
+            return [_define, v, exp]
+    elif x[0] is _begin:
+        if len(x)==1: return None        # (begin) => None
+        else: return [expand(xi, toplevel) for xi in x]
+    elif x[0] is _lambda:                # (lambda (x) e1 e2)
+        require(x, len(x)>=3)            #  => (lambda (x) (begin e1 e2))
+        vars, body = x[1], x[2:]
+        require(x, (isa(vars, list) and all(isa(v, Symbol) for v in vars))
+                or isa(vars, Symbol), "illegal lambda argument list")
+        exp = body[0] if len(body) == 1 else [_begin] + body
+        return [_lambda, vars, expand(exp)]
+    elif x[0] is _quasiquote:            # `x => expand_quasiquote(x)
+        require(x, len(x)==2)
+        return expand_quasiquote(x[1])
+    elif isa(x[0], Symbol) and x[0] in macro_table:
+        return expand(macro_table[x[0]](*x[1:]), toplevel) # (m arg...)
+    else:                                #        => macroexpand if m isa macro
+        return list(map(expand, x))            # (f arg...) => expand each
+
+def require(x, predicate, msg="wrong length"):
+    "Signal a syntax error if predicate is false."
+    if not predicate: raise SyntaxError(to_string(x)+': '+msg)
+
+_append, _cons, _let = map(Sym, "append cons let".split())
+
+def expand_quasiquote(x):
+    """Expand `x => 'x; `,x => x; `(,@x y) => (append x y) """
+    if not is_pair(x):
+        return [_quote, x]
+    require(x, x[0] is not _unquotesplicing, "can't splice here")
+    if x[0] is _unquote:
+        require(x, len(x)==2)
+        return x[1]
+    elif is_pair(x[0]) and x[0][0] is _unquotesplicing:
+        require(x[0], len(x[0])==2)
+        return [_append, x[0][1], expand_quasiquote(x[1:])]
+    else:
+        return [_cons, expand_quasiquote(x[0]), expand_quasiquote(x[1:])]
+
+def let(*args):
+    args = list(args)
+    x = cons(_let, args)
+    require(x, len(args)>1)
+    bindings, body = args[0], args[1:]
+    require(x, all(isa(b, list) and len(b)==2 and isa(b[0], Symbol)
+                   for b in bindings), "illegal binding list")
+    vars, vals = zip(*bindings)
+    return [[_lambda, list(vars)]+list(map(expand, body))] + list(map(expand, vals))
+
+macro_table = {_let:let} ## More macros can go here
+
+eval(parse("""(begin
+
+(define-macro and (lambda args
+   (if (null? args) #t
+       (if (= (length args) 1) (car args)
+           `(if ,(car args) (and ,@(cdr args)) #f)))))
+
+;; More macros can also go here
+
+)"""))
+
+if __name__ == '__main__':
+    repl()

18-context-mngr/lispy/original/lispytest.py

@@ -0,0 +1,122 @@
+from __future__ import print_function
+
+################ Tests for lis.py and lispy.py
+
+lis_tests = [
+    ("(quote (testing 1 (2.0) -3.14e159))", ['testing', 1, [2.0], -3.14e159]),
+    ("(+ 2 2)", 4),
+    ("(+ (* 2 100) (* 1 10))", 210),
+    ("(if (> 6 5) (+ 1 1) (+ 2 2))", 2),
+    ("(if (< 6 5) (+ 1 1) (+ 2 2))", 4),
+    ("(define x 3)", None), ("x", 3), ("(+ x x)", 6),
+    ("((lambda (x) (+ x x)) 5)", 10),
+    ("(define twice (lambda (x) (* 2 x)))", None), ("(twice 5)", 10),
+    ("(define compose (lambda (f g) (lambda (x) (f (g x)))))", None),
+    ("((compose list twice) 5)", [10]),
+    ("(define repeat (lambda (f) (compose f f)))", None),
+    ("((repeat twice) 5)", 20), ("((repeat (repeat twice)) 5)", 80),
+    ("(define fact (lambda (n) (if (<= n 1) 1 (* n (fact (- n 1))))))", None),
+    ("(fact 3)", 6),
+    ("(fact 50)", 30414093201713378043612608166064768844377641568960512000000000000),
+    ("(define abs (lambda (n) ((if (> n 0) + -) 0 n)))", None),
+    ("(list (abs -3) (abs 0) (abs 3))", [3, 0, 3]),
+    ("""(define combine (lambda (f)
+    (lambda (x y)
+      (if (null? x) (quote ())
+          (f (list (car x) (car y))
+             ((combine f) (cdr x) (cdr y)))))))""", None),
+    ("(define zip (combine cons))", None),
+    ("(zip (list 1 2 3 4) (list 5 6 7 8))", [[1, 5], [2, 6], [3, 7], [4, 8]]),
+    ("""(define riff-shuffle (lambda (deck) (begin
+    (define take (lambda (n seq) (if (<= n 0) (quote ()) (cons (car seq) (take (- n 1) (cdr seq))))))
+    (define drop (lambda (n seq) (if (<= n 0) seq (drop (- n 1) (cdr seq)))))
+    (define mid (lambda (seq) (/ (length seq) 2)))
+    ((combine append) (take (mid deck) deck) (drop (mid deck) deck)))))""", None),
+    ("(riff-shuffle (list 1 2 3 4 5 6 7 8))", [1, 5, 2, 6, 3, 7, 4, 8]),
+    ("((repeat riff-shuffle) (list 1 2 3 4 5 6 7 8))",  [1, 3, 5, 7, 2, 4, 6, 8]),
+    ("(riff-shuffle (riff-shuffle (riff-shuffle (list 1 2 3 4 5 6 7 8))))", [1,2,3,4,5,6,7,8]),
+    ]
+
+lispy_tests = [
+    ("()", SyntaxError), ("(set! x)", SyntaxError), 
+    ("(define 3 4)", SyntaxError),
+    ("(quote 1 2)", SyntaxError), ("(if 1 2 3 4)", SyntaxError), 
+    ("(lambda 3 3)", SyntaxError), ("(lambda (x))", SyntaxError),
+    ("""(if (= 1 2) (define-macro a 'a) 
+     (define-macro a 'b))""", SyntaxError),
+    ("(define (twice x) (* 2 x))", None), ("(twice 2)", 4),
+    ("(twice 2 2)", TypeError),
+    ("(define lyst (lambda items items))", None),
+    ("(lyst 1 2 3 (+ 2 2))", [1,2,3,4]),
+    ("(if 1 2)", 2),
+    ("(if (= 3 4) 2)", None),
+    ("(begin (define x 1) (set! x (+ x 1)) (+ x 1))", 3),
+    ("(define ((account bal) amt) (set! bal (+ bal amt)) bal)", None),
+    ("(define a1 (account 100))", None),
+    ("(a1 0)", 100), ("(a1 10)", 110), ("(a1 10)", 120),
+    ("""(define (newton guess function derivative epsilon)
+    (define guess2 (- guess (/ (function guess) (derivative guess))))
+    (if (< (abs (- guess guess2)) epsilon) guess2
+        (newton guess2 function derivative epsilon)))""", None),
+    ("""(define (square-root a)
+    (newton 1 (lambda (x) (- (* x x) a)) (lambda (x) (* 2 x)) 1e-8))""", None),
+    ("(> (square-root 200.) 14.14213)", True),
+    ("(< (square-root 200.) 14.14215)", True),
+    ("(= (square-root 200.) (sqrt 200.))", True),
+    ("""(define (sum-squares-range start end)
+         (define (sumsq-acc start end acc)
+            (if (> start end) acc (sumsq-acc (+ start 1) end (+ (* start start) acc))))
+         (sumsq-acc start end 0))""", None),
+    ("(sum-squares-range 1 3000)", 9004500500), ## Tests tail recursion
+    ("(call/cc (lambda (throw) (+ 5 (* 10 (throw 1))))) ;; throw", 1),
+    ("(call/cc (lambda (throw) (+ 5 (* 10 1)))) ;; do not throw", 15),
+    ("""(call/cc (lambda (throw) 
+         (+ 5 (* 10 (call/cc (lambda (escape) (* 100 (escape 3)))))))) ; 1 level""", 35),
+    ("""(call/cc (lambda (throw) 
+         (+ 5 (* 10 (call/cc (lambda (escape) (* 100 (throw 3)))))))) ; 2 levels""", 3),
+    ("""(call/cc (lambda (throw) 
+         (+ 5 (* 10 (call/cc (lambda (escape) (* 100 1))))))) ; 0 levels""", 1005),
+    ("(* 1i 1i)", -1), ("(sqrt -1)", 1j),
+    ("(let ((a 1) (b 2)) (+ a b))", 3),
+    ("(let ((a 1) (b 2 3)) (+ a b))", SyntaxError),
+    ("(and 1 2 3)", 3), ("(and (> 2 1) 2 3)", 3), ("(and)", True),
+    ("(and (> 2 1) (> 2 3))", False),
+    ("(define-macro unless (lambda args `(if (not ,(car args)) (begin ,@(cdr args))))) ; test `", None),
+    ("(unless (= 2 (+ 1 1)) (display 2) 3 4)", None),
+    (r'(unless (= 4 (+ 1 1)) (display 2) (display "\n") 3 4)', 4),
+    ("(quote x)", 'x'), 
+    ("(quote (1 2 three))", [1, 2, 'three']), 
+    ("'x", 'x'),
+    ("'(one 2 3)", ['one', 2, 3]),
+    ("(define L (list 1 2 3))", None),
+    ("`(testing ,@L testing)", ['testing',1,2,3,'testing']),
+    ("`(testing ,L testing)", ['testing',[1,2,3],'testing']),
+    ("`,@L", SyntaxError),
+    ("""'(1 ;test comments '
+     ;skip this line
+     2 ; more ; comments ; ) )
+     3) ; final comment""", [1,2,3]),
+    ]
+
+def test(tests, name=''):
+    "For each (exp, expected) test case, see if eval(parse(exp)) == expected."
+    fails = 0
+    for (x, expected) in tests:
+        try:
+            result = eval(parse(x))
+            print(x, '=>', lispstr(result))
+            ok = (result == expected)
+        except Exception as e:
+            print(x, '=raises=>', type(e).__name__, e)
+            ok = isinstance(expected, type) and issubclass(expected, Exception) and isinstance(e, expected)
+        if not ok:
+            fails += 1
+            print('FAIL!!!  Expected', expected)
+    print('%s %s: %d out of %d tests fail.' % ('*'*45, name, fails, len(tests)))
+
+if __name__ == '__main__':
+    from lis import *
+    test(lis_tests, 'lis.py')
+    from lispy import *
+    test(lis_tests+lispy_tests, 'lispy.py')
+    

18-context-mngr/lispy/py3.10/lis.py

@@ -0,0 +1,160 @@
+################ Lispy: Scheme Interpreter in Python 3.9
+
+## (c) Peter Norvig, 2010-18; See http://norvig.com/lispy.html
+## Minor edits for Fluent Python, Second Edition (O'Reilly, 2021)
+## by Luciano Ramalho, adding type hints and pattern matching.
+
+################ Imports and Types
+
+import math
+import operator as op
+from collections import ChainMap
+from collections.abc import MutableMapping
+from typing import Any, TypeAlias
+
+Atom: TypeAlias = float | int | str
+Expression: TypeAlias = Atom | list
+
+Environment: TypeAlias = MutableMapping[str, object]
+
+
+class Procedure:
+    "A user-defined Scheme procedure."
+
+    def __init__(self, parms: list[str], body: Expression, env: Environment):
+        self.parms, self.body, self.env = parms, body, env
+
+    def __call__(self, *args: Expression) -> Any:
+        env: Environment = ChainMap(dict(zip(self.parms, args)), self.env)
+        return evaluate(self.body, env)
+
+
+################ Global Environment
+
+
+def standard_env() -> Environment:
+    "An environment with some Scheme standard procedures."
+    env: Environment = {}
+    env.update(vars(math))   # sin, cos, sqrt, pi, ...
+    env.update(
+        {
+            '+': op.add,
+            '-': op.sub,
+            '*': op.mul,
+            '/': op.truediv,
+            '>': op.gt,
+            '<': op.lt,
+            '>=': op.ge,
+            '<=': op.le,
+            '=': op.eq,
+            'abs': abs,
+            'append': op.add,
+            'apply': lambda proc, args: proc(*args),
+            'begin': lambda *x: x[-1],
+            'car': lambda x: x[0],
+            'cdr': lambda x: x[1:],
+            'cons': lambda x, y: [x] + y,
+            'eq?': op.is_,
+            'equal?': op.eq,
+            'length': len,
+            'list': lambda *x: list(x),
+            'list?': lambda x: isinstance(x, list),
+            'map': lambda *args: list(map(*args)),
+            'max': max,
+            'min': min,
+            'not': op.not_,
+            'null?': lambda x: x == [],
+            'number?': lambda x: isinstance(x, (int, float)),
+            'procedure?': callable,
+            'round': round,
+            'symbol?': lambda x: isinstance(x, str),
+        }
+    )
+    return env
+
+
+global_env: Environment = standard_env()
+
+################ Parsing: parse, tokenize, and read_from_tokens
+
+
+def parse(program: str) -> Expression:
+    "Read a Scheme expression from a string."
+    return read_from_tokens(tokenize(program))
+
+
+def tokenize(s: str) -> list[str]:
+    "Convert a string into a list of tokens."
+    return s.replace('(', ' ( ').replace(')', ' ) ').split()
+
+
+def read_from_tokens(tokens: list[str]) -> Expression:
+    "Read an expression from a sequence of tokens."
+    if len(tokens) == 0:
+        raise SyntaxError('unexpected EOF while reading')
+    token = tokens.pop(0)
+    if '(' == token:
+        L = []
+        while tokens[0] != ')':
+            L.append(read_from_tokens(tokens))
+        tokens.pop(0)   # pop off ')'
+        return L
+    elif ')' == token:
+        raise SyntaxError('unexpected )')
+    else:
+        return parse_atom(token)
+
+
+def parse_atom(token: str) -> Atom:
+    "Numbers become numbers; every other token is a symbol."
+    try:
+        return int(token)
+    except ValueError:
+        try:
+            return float(token)
+        except ValueError:
+            return str(token)
+
+
+################ Interaction: A REPL
+
+
+def repl(prompt: str = 'lis.py> ') -> None:
+    "A prompt-read-evaluate-print loop."
+    while True:
+        val = evaluate(parse(input(prompt)))
+        if val is not None:
+            print(lispstr(val))
+
+
+def lispstr(exp: object) -> str:
+    "Convert a Python object back into a Lisp-readable string."
+    if isinstance(exp, list):
+        return '(' + ' '.join(map(lispstr, exp)) + ')'
+    else:
+        return str(exp)
+
+
+################ eval
+
+
+def evaluate(x: Expression, env: Environment = global_env) -> Any:
+    "Evaluate an expression in an environment."
+    match x:
+        case str():                               # variable reference
+            return env[x]
+        case literal if not isinstance(x, list):  # constant literal
+            return literal
+        case ['quote', exp]:                      # (quote exp)
+            return exp
+        case ['if', test, conseq, alt]:           # (if test conseq alt)
+            exp = conseq if evaluate(test, env) else alt
+            return evaluate(exp, env)
+        case ['define', var, exp]:                # (define var exp)
+            env[var] = evaluate(exp, env)
+        case ['lambda', parms, body]:             # (lambda (var...) body)
+            return Procedure(parms, body, env)
+        case [op, *args]:                         # (proc arg...)
+            proc = evaluate(op, env)
+            values = (evaluate(arg, env) for arg in args)
+            return proc(*values)

18-context-mngr/lispy/py3.10/lis_test.py

@@ -0,0 +1,147 @@
+from typing import Optional
+
+from pytest import mark
+
+from lis import parse, evaluate, Expression, Environment, standard_env
+
+
+@mark.parametrize( 'source, expected', [
+    ("(quote (testing 1 (2.0) -3.14e159))", ['testing', 1, [2.0], -3.14e159]),
+    ("(+ 2 2)", 4),
+    ("(+ (* 2 100) (* 1 10))", 210),
+    ("(if (> 6 5) (+ 1 1) (+ 2 2))", 2),
+    ("(if (< 6 5) (+ 1 1) (+ 2 2))", 4),
+    ("(define x 3)", None), ("x", 3), ("(+ x x)", 6),
+    ("((lambda (x) (+ x x)) 5)", 10),
+    ("(define twice (lambda (x) (* 2 x)))", None), ("(twice 5)", 10),
+    ("(define compose (lambda (f g) (lambda (x) (f (g x)))))", None),
+    ("((compose list twice) 5)", [10]),
+    ("(define repeat (lambda (f) (compose f f)))", None),
+    ("((repeat twice) 5)", 20), ("((repeat (repeat twice)) 5)", 80),
+    ("(define fact (lambda (n) (if (<= n 1) 1 (* n (fact (- n 1))))))", None),
+    ("(fact 3)", 6),
+    ("(fact 50)", 30414093201713378043612608166064768844377641568960512000000000000),
+    ("(define abs (lambda (n) ((if (> n 0) + -) 0 n)))", None),
+    ("(list (abs -3) (abs 0) (abs 3))", [3, 0, 3]),
+    ("""(define combine (lambda (f)
+    (lambda (x y)
+      (if (null? x) (quote ())
+          (f (list (car x) (car y))
+             ((combine f) (cdr x) (cdr y)))))))""", None),
+    ("(define zip (combine cons))", None),
+    ("(zip (list 1 2 3 4) (list 5 6 7 8))", [[1, 5], [2, 6], [3, 7], [4, 8]]),
+    ("""(define riff-shuffle (lambda (deck) (begin
+    (define take (lambda (n seq) (if (<= n 0) (quote ()) (cons (car seq) (take (- n 1) (cdr seq))))))
+    (define drop (lambda (n seq) (if (<= n 0) seq (drop (- n 1) (cdr seq)))))
+    (define mid (lambda (seq) (/ (length seq) 2)))
+    ((combine append) (take (mid deck) deck) (drop (mid deck) deck)))))""", None),
+    ("(riff-shuffle (list 1 2 3 4 5 6 7 8))", [1, 5, 2, 6, 3, 7, 4, 8]),
+    ("((repeat riff-shuffle) (list 1 2 3 4 5 6 7 8))",  [1, 3, 5, 7, 2, 4, 6, 8]),
+    ("(riff-shuffle (riff-shuffle (riff-shuffle (list 1 2 3 4 5 6 7 8))))", [1,2,3,4,5,6,7,8]),
+])
+@mark.skip
+def test_evaluate(source: str, expected: Optional[Expression]) -> None:
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+# tests for each of the cases in evaluate
+
+def test_evaluate_variable() -> None:
+    env: Environment = dict(x=10)
+    source = 'x'
+    expected = 10
+    got = evaluate(parse(source), env)
+    assert got == expected
+
+
+def test_evaluate_literal() -> None:
+    source = '3.3'
+    expected = 3.3
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+def test_evaluate_quote() -> None:
+    source = '(quote (1.1 is not 1))'
+    expected = [1.1, 'is', 'not', 1]
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+def test_evaluate_if_true() -> None:
+    source = '(if 1 10 no-such-thing)'
+    expected = 10
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+def test_evaluate_if_false() -> None:
+    source = '(if 0 no-such-thing 20)'
+    expected = 20
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+def test_define() -> None:
+    env: Environment = standard_env()
+    source = '(define answer (* 6 7))'
+    got = evaluate(parse(source), env)
+    assert got is None
+    assert env['answer'] == 42
+
+
+def test_lambda() -> None:
+    env: Environment = standard_env()
+    source = '(lambda (a b) (if (>= a b) a b))'
+    func = evaluate(parse(source), env)
+    assert func.parms == ['a', 'b']
+    assert func.body == ['if', ['>=', 'a', 'b'], 'a', 'b']
+    assert func.env is env
+    assert func(1, 2) == 2
+    assert func(3, 2) == 3
+
+
+def test_begin() -> None:
+    env: Environment = standard_env()
+    source = """
+        (begin
+            (define x (* 2 3))
+            (* x 7)
+        )
+        """
+    got = evaluate(parse(source), env)
+    assert got == 42
+
+
+def test_invocation_builtin_car() -> None:
+    env: Environment = standard_env()
+    source = '(car (quote (11 22 33)))'
+    got = evaluate(parse(source), env)
+    assert got == 11
+
+
+def test_invocation_builtin_append() -> None:
+    env: Environment = standard_env()
+    source = '(append (quote (a b)) (quote (c d)))'
+    got = evaluate(parse(source), env)
+    assert got == ['a', 'b', 'c', 'd']
+
+
+def test_invocation_builtin_map() -> None:
+    env: Environment = standard_env()
+    source = '(map (lambda (x) (* x 2)) (quote (1 2 3))))'
+    got = evaluate(parse(source), env)
+    assert got == [2, 4, 6]
+
+
+def test_invocation_user_procedure() -> None:
+    env: Environment = standard_env()
+    source = """
+        (begin
+            (define max (lambda (a b) (if (>= a b) a b)))
+            (max 22 11)
+        )
+        """
+    got = evaluate(parse(source), env)
+    assert got == 22

18-context-mngr/lispy/py3.9/lis.py

@@ -0,0 +1,163 @@
+################ Lispy: Scheme Interpreter in Python 3.9
+
+## (c) Peter Norvig, 2010-18; See http://norvig.com/lispy.html
+## Minor edits for Fluent Python, Second Edition (O'Reilly, 2021)
+## by Luciano Ramalho, mostly adding type hints.
+
+################ Imports and Types
+
+import math
+import operator as op
+from collections import ChainMap
+from collections.abc import MutableMapping
+from typing import Union, Any
+
+Atom = Union[float, int, str]
+Expression = Union[Atom, list]
+
+Environment = MutableMapping[str, object]
+
+
+class Procedure:
+    "A user-defined Scheme procedure."
+
+    def __init__(self, parms: list[str], body: Expression, env: Environment):
+        self.parms, self.body, self.env = parms, body, env
+
+    def __call__(self, *args: Expression) -> Any:
+        env: Environment = ChainMap(dict(zip(self.parms, args)), self.env)
+        return evaluate(self.body, env)
+
+
+################ Global Environment
+
+
+def standard_env() -> Environment:
+    "An environment with some Scheme standard procedures."
+    env: Environment = {}
+    env.update(vars(math))   # sin, cos, sqrt, pi, ...
+    env.update(
+        {
+            '+': op.add,
+            '-': op.sub,
+            '*': op.mul,
+            '/': op.truediv,
+            '>': op.gt,
+            '<': op.lt,
+            '>=': op.ge,
+            '<=': op.le,
+            '=': op.eq,
+            'abs': abs,
+            'append': op.add,
+            'apply': lambda proc, args: proc(*args),
+            'begin': lambda *x: x[-1],
+            'car': lambda x: x[0],
+            'cdr': lambda x: x[1:],
+            'cons': lambda x, y: [x] + y,
+            'eq?': op.is_,
+            'equal?': op.eq,
+            'length': len,
+            'list': lambda *x: list(x),
+            'list?': lambda x: isinstance(x, list),
+            'map': lambda *args: list(map(*args)),
+            'max': max,
+            'min': min,
+            'not': op.not_,
+            'null?': lambda x: x == [],
+            'number?': lambda x: isinstance(x, (int, float)),
+            'procedure?': callable,
+            'round': round,
+            'symbol?': lambda x: isinstance(x, str),
+        }
+    )
+    return env
+
+
+global_env: Environment = standard_env()
+
+################ Parsing: parse, tokenize, and read_from_tokens
+
+
+def parse(program: str) -> Expression:
+    "Read a Scheme expression from a string."
+    return read_from_tokens(tokenize(program))
+
+
+def tokenize(s: str) -> list[str]:
+    "Convert a string into a list of tokens."
+    return s.replace('(', ' ( ').replace(')', ' ) ').split()
+
+
+def read_from_tokens(tokens: list[str]) -> Expression:
+    "Read an expression from a sequence of tokens."
+    if len(tokens) == 0:
+        raise SyntaxError('unexpected EOF while reading')
+    token = tokens.pop(0)
+    if '(' == token:
+        L = []
+        while tokens[0] != ')':
+            L.append(read_from_tokens(tokens))
+        tokens.pop(0)   # pop off ')'
+        return L
+    elif ')' == token:
+        raise SyntaxError('unexpected )')
+    else:
+        return parse_atom(token)
+
+
+def parse_atom(token: str) -> Atom:
+    "Numbers become numbers; every other token is a symbol."
+    try:
+        return int(token)
+    except ValueError:
+        try:
+            return float(token)
+        except ValueError:
+            return str(token)
+
+
+################ Interaction: A REPL
+
+
+def repl(prompt: str = 'lis.py> ') -> None:
+    "A prompt-read-evaluate-print loop."
+    while True:
+        val = evaluate(parse(input(prompt)))
+        if val is not None:
+            print(lispstr(val))
+
+
+def lispstr(exp: object) -> str:
+    "Convert a Python object back into a Lisp-readable string."
+    if isinstance(exp, list):
+        return '(' + ' '.join(map(lispstr, exp)) + ')'
+    else:
+        return str(exp)
+
+
+################ eval
+
+
+def evaluate(x: Expression, env: Environment = global_env) -> Any:
+    "Evaluate an expression in an environment."
+    if isinstance(x, str):         # variable reference
+        return env[x]
+    elif not isinstance(x, list):  # constant literal
+        return x
+    elif x[0] == 'quote':          # (quote exp)
+        (_, exp) = x
+        return exp
+    elif x[0] == 'if':             # (if test conseq alt)
+        (_, test, conseq, alt) = x
+        exp = conseq if evaluate(test, env) else alt
+        return evaluate(exp, env)
+    elif x[0] == 'define':         # (define var exp)
+        (_, var, exp) = x
+        env[var] = evaluate(exp, env)
+    elif x[0] == 'lambda':         # (lambda (var...) body)
+        (_, parms, body) = x
+        return Procedure(parms, body, env)
+    else:                          # (proc arg...)
+        proc = evaluate(x[0], env)
+        args = [evaluate(exp, env) for exp in x[1:]]
+        return proc(*args)

18-context-mngr/lispy/py3.9/lis_test.py

@@ -0,0 +1,147 @@
+from typing import Optional
+
+from pytest import mark
+
+from lis import parse, evaluate, Expression, Environment, standard_env
+
+
+@mark.parametrize( 'source, expected', [
+    ("(quote (testing 1 (2.0) -3.14e159))", ['testing', 1, [2.0], -3.14e159]),
+    ("(+ 2 2)", 4),
+    ("(+ (* 2 100) (* 1 10))", 210),
+    ("(if (> 6 5) (+ 1 1) (+ 2 2))", 2),
+    ("(if (< 6 5) (+ 1 1) (+ 2 2))", 4),
+    ("(define x 3)", None), ("x", 3), ("(+ x x)", 6),
+    ("((lambda (x) (+ x x)) 5)", 10),
+    ("(define twice (lambda (x) (* 2 x)))", None), ("(twice 5)", 10),
+    ("(define compose (lambda (f g) (lambda (x) (f (g x)))))", None),
+    ("((compose list twice) 5)", [10]),
+    ("(define repeat (lambda (f) (compose f f)))", None),
+    ("((repeat twice) 5)", 20), ("((repeat (repeat twice)) 5)", 80),
+    ("(define fact (lambda (n) (if (<= n 1) 1 (* n (fact (- n 1))))))", None),
+    ("(fact 3)", 6),
+    ("(fact 50)", 30414093201713378043612608166064768844377641568960512000000000000),
+    ("(define abs (lambda (n) ((if (> n 0) + -) 0 n)))", None),
+    ("(list (abs -3) (abs 0) (abs 3))", [3, 0, 3]),
+    ("""(define combine (lambda (f)
+    (lambda (x y)
+      (if (null? x) (quote ())
+          (f (list (car x) (car y))
+             ((combine f) (cdr x) (cdr y)))))))""", None),
+    ("(define zip (combine cons))", None),
+    ("(zip (list 1 2 3 4) (list 5 6 7 8))", [[1, 5], [2, 6], [3, 7], [4, 8]]),
+    ("""(define riff-shuffle (lambda (deck) (begin
+    (define take (lambda (n seq) (if (<= n 0) (quote ()) (cons (car seq) (take (- n 1) (cdr seq))))))
+    (define drop (lambda (n seq) (if (<= n 0) seq (drop (- n 1) (cdr seq)))))
+    (define mid (lambda (seq) (/ (length seq) 2)))
+    ((combine append) (take (mid deck) deck) (drop (mid deck) deck)))))""", None),
+    ("(riff-shuffle (list 1 2 3 4 5 6 7 8))", [1, 5, 2, 6, 3, 7, 4, 8]),
+    ("((repeat riff-shuffle) (list 1 2 3 4 5 6 7 8))",  [1, 3, 5, 7, 2, 4, 6, 8]),
+    ("(riff-shuffle (riff-shuffle (riff-shuffle (list 1 2 3 4 5 6 7 8))))", [1,2,3,4,5,6,7,8]),
+])
+@mark.skip
+def test_evaluate(source: str, expected: Optional[Expression]) -> None:
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+# tests for each of the cases in evaluate
+
+def test_evaluate_variable() -> None:
+    env: Environment = dict(x=10)
+    source = 'x'
+    expected = 10
+    got = evaluate(parse(source), env)
+    assert got == expected
+
+
+def test_evaluate_literal() -> None:
+    source = '3.3'
+    expected = 3.3
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+def test_evaluate_quote() -> None:
+    source = '(quote (1.1 is not 1))'
+    expected = [1.1, 'is', 'not', 1]
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+def test_evaluate_if_true() -> None:
+    source = '(if 1 10 no-such-thing)'
+    expected = 10
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+def test_evaluate_if_false() -> None:
+    source = '(if 0 no-such-thing 20)'
+    expected = 20
+    got = evaluate(parse(source))
+    assert got == expected
+
+
+def test_define() -> None:
+    env: Environment = standard_env()
+    source = '(define answer (* 6 7))'
+    got = evaluate(parse(source), env)
+    assert got is None
+    assert env['answer'] == 42
+
+
+def test_lambda() -> None:
+    env: Environment = standard_env()
+    source = '(lambda (a b) (if (>= a b) a b))'
+    func = evaluate(parse(source), env)
+    assert func.parms == ['a', 'b']
+    assert func.body == ['if', ['>=', 'a', 'b'], 'a', 'b']
+    assert func.env is env
+    assert func(1, 2) == 2
+    assert func(3, 2) == 3
+
+
+def test_begin() -> None:
+    env: Environment = standard_env()
+    source = """
+        (begin
+            (define x (* 2 3))
+            (* x 7)
+        )
+        """
+    got = evaluate(parse(source), env)
+    assert got == 42
+
+
+def test_invocation_builtin_car() -> None:
+    env: Environment = standard_env()
+    source = '(car (quote (11 22 33)))'
+    got = evaluate(parse(source), env)
+    assert got == 11
+
+
+def test_invocation_builtin_append() -> None:
+    env: Environment = standard_env()
+    source = '(append (quote (a b)) (quote (c d)))'
+    got = evaluate(parse(source), env)
+    assert got == ['a', 'b', 'c', 'd']
+
+
+def test_invocation_builtin_map() -> None:
+    env: Environment = standard_env()
+    source = '(map (lambda (x) (* x 2)) (quote (1 2 3))))'
+    got = evaluate(parse(source), env)
+    assert got == [2, 4, 6]
+
+
+def test_invocation_user_procedure() -> None:
+    env: Environment = standard_env()
+    source = """
+        (begin
+            (define max (lambda (a b) (if (>= a b) a b)))
+            (max 22 11)
+        )
+        """
+    got = evaluate(parse(source), env)
+    assert got == 22

22-async/mojifinder/tcp_mojifinder.py

@@ -1,9 +1,11 @@
 #!/usr/bin/env python3
 
 # tag::TCP_MOJIFINDER_TOP[]
-import sys
 import asyncio
 import functools
+import sys
+from asyncio.trsock import TransportSocket
+from typing import cast
 
 from charindex import InvertedIndex, format_results  # <1>
 
@@ -54,17 +56,19 @@ async def supervisor(index: InvertedIndex, host: str, port: int):
     server = await asyncio.start_server(    # <1>
         functools.partial(finder, index),   # <2>
         host, port)                         # <3>
-    addr = server.sockets[0].getsockname()  # type: ignore  # <4>
-    print(f'Serving on {addr}. Hit CTRL-C to stop.')
-    await server.serve_forever()  # <5>
+
+    socket_list = cast(tuple[TransportSocket, ...], server.sockets)  # <4>
+    addr = socket_list[0].getsockname()
+    print(f'Serving on {addr}. Hit CTRL-C to stop.')  # <5>
+    await server.serve_forever()  # <6>
 
 def main(host: str = '127.0.0.1', port_arg: str = '2323'):
     port = int(port_arg)
     print('Building index.')
-    index = InvertedIndex()                         # <6>
+    index = InvertedIndex()                         # <7>
     try:
-        asyncio.run(supervisor(index, host, port))  # <7>
-    except KeyboardInterrupt:                       # <8>
+        asyncio.run(supervisor(index, host, port))  # <8>
+    except KeyboardInterrupt:                       # <9>
         print('\nServer shut down.')
 
 if __name__ == '__main__':

25-class-metaprog/checked/decorator/checkeddeco.py

@@ -96,7 +96,7 @@ def checked(cls: type) -> type:  # <1>
     for name, constructor in _fields(cls).items():    # <2>
         setattr(cls, name, Field(name, constructor))  # <3>
 
-    cls._fields = classmethod(_fields)  #type: ignore  # <4>
+    cls._fields = classmethod(_fields)  # type: ignore  # <4>
 
     instance_methods = (  # <5>
         __init__,