brainf 解释器，但它是一个 Python 表达式
(lambda cod, _, inp: (lambda *, _cp = 0, _mp = 0, _ip = 0, _mem = {}, _inp = inp
.encode(), _out = b"": next(__import__("sys").stdout.buffer.write(_out) and None
or None for _ in __import__("itertools").count() if not (_mem.__setitem__(_mp, (
(_mem[_mp] if _mp in _mem else 0) + (1 if cod[_cp] == "+" else -1 if cod[_cp] ==
"-" else 0)) & 255) and 0 or (_mp := _mp + (1 if cod[_cp] == ">" else -1 if cod[
_cp] == "<" else 0)) and 0 or ((_cp := (lambda si, *, _d = 0: next(i for i in (
range(si, len(cod)) if cod[si] == "[" else range(si, -1, -1)) if cod[i] in "[]"
and ((_d := _d + (1 if cod[i] == "[" else -1)) == 0)))(_cp)) if cod[_cp] in "[]"
and bool(_mem[_mp] if _mp in _mem else 0) == bool(cod[_cp] == "]") else 0) and 0
or ((_out := _out + bytes((_mem[_mp],))) if cod[_cp] == "." else _mem.__setitem__
(_mp, _inp[_ip]) and 0 or (_ip := _ip + 1) if cod[_cp] == "," and _ip < len(_inp)
else 0) and 0 or (_cp := _cp + 1) < len(cod))))())(*__import__("sys").stdin.read
().partition("!"))
在群友的怂恿下挑战用 Python 但不用 def 关键字和 exec()、eval() 函数实现 brainf 解释器，但我决定做得更绝一些。于是就有了这个单个表达式的 brainf 解释器。
此解释器从标准输入读取 brainf 代码和程序输入（用半角叹号分隔），程序输出直接发送到标准输出（在 Python IDLE 中可能无效）；将“__import__("sys").stdout.buffer.write(_out) and None or None”改为“_out”可变为以 bytes 类型返回输出内容。
大量使用了“and 0 or”来分隔“语句”，这相当于一些其他编程语言中的逗号运算符。使用赋值运算 := 和字典的 __setitem__() 方法来进行赋值。循环结构全部用生成器表达式（Generator expressions）实现：使用了 ... for _ in itertools.count() 来实现无限循环，并使用 next(... for ... if ...) 的写法来在满足特定条件时跳出循环。
带缩进版：
(lambda cod, _, inp:
(lambda *, _cp = 0, _mp = 0, _ip = 0, _mem = {}, _inp = inp .encode(), _out = b"": next(
__import__("sys").stdout.buffer.write(_out) and None or None
for _ in __import__("itertools").count()
if not (
_mem.__setitem__(
_mp,
((_mem[_mp] if _mp in _mem else 0) + (1 if cod[_cp] == "+" else -1 if cod[_cp] == "-" else 0)) & 255
) and 0 or
(_mp := _mp + (1 if cod[_cp] == ">" else -1 if cod[ _cp] == "<" else 0)) and 0 or
(
(_cp := (lambda si, *, _d = 0:
next(i
for i in (range(si, len(cod)) if cod[si] == "[" else range(si, -1, -1))
if cod[i] in "[]" and ((_d := _d + (1 if cod[i] == "[" else -1)) == 0)
)
)(_cp))
if cod[_cp] in "[]" and bool(_mem[_mp] if _mp in _mem else 0) == bool(cod[_cp] == "]")
else 0
) and 0 or
(
(_out := _out + bytes((_mem[_mp],))) if cod[_cp] == "."
else _mem.__setitem__(_mp, _inp[_ip]) and 0 or (_ip := _ip + 1) if cod[_cp] == "," and _ip < len(_inp)
else 0
) and 0 or
(_cp := _cp + 1) < len(cod)
)
))()
)(*__import__("sys").stdin.read ().partition("!"))