_F.py

from functools import partial

itself = lambda x: x
plus = lambda x, y: x + y
minus = lambda x, y: x - y


class _FBase:
    def __init__(self, f1=itself):
        self.f1 = f1

    def __add__(self, val):
        if isinstance(val, _FBase):
            return _FBinary(plus, self, val)
        else:
            return _FBase(partial(plus, val))

    def __sub__(self, val):
        if isinstance(val, _FBase):
            return _FBinary(minus, self, val)
        else:
            return _FBase(partial(minus, 3))

    def __call__(self, args):
        if self._is_list_args(args) and len(args) == 1:
            return self.f1(args[0])
        else:
            return self.f1(args)

    def _is_list_args(self, args):
        return isinstance(args, tuple) or isinstance(args, list)


class _FBinary(_FBase):
    def __init__(self, op, f1, f2):
        self.op = op
        self.f1 = f1
        self.f2 = f2

    def __call__(self, args):
        if self._is_list_args(args):
            rest, last = args[:-1], args[-1]
            ex, ey = self.f1(rest), self.f2(last)
            return self.op(ex, ey)


class _FPos(_FBase):
    def __init__(self, pos, f1=itself):
        super(_FPos, self).__init__(f1)
        self.pos = pos

    def __add__(self, val):
        if isinstance(val, _FBase):
            return _FBinaryPos(plus, self, val)
        else:
            return _FPos(self.pos, partial(plus, val))

    def __call__(self, args, pos_args=None):
        if pos_args is None:
            return self.f1(args[self.pos])
        elif self._is_list_args(args) and len(args) == 1:
            return self.f1(pos_args[self.pos])
        else:
            return pos_args[self.pos]


class _FBinaryPos(_FPos):
    def __init__(self, op, f1, f2):
        self.op = op
        self.f1 = f1
        self.f2 = f2
        self.fpos = None

    def __call__(self, args, pos_args=None):
        # this happens only on the top-level call
        if pos_args == None:
            pos_args = args

        if self._is_list_args(args):
            rest, last = args[:-1], args[-1]
            ex, ey = self.f1(rest, pos_args), self.f2(last, pos_args)
            return self.op(ex, ey)


_ = _FBase()
_0 = _FPos(0)
_1 = _FPos(1)
_2 = _FPos(2)

m = map(_0 + _1 + _2, [(1, 2, 3)])
m = map(_ + 3, [1, 2, 3])
m = map(_ + _, [(1, 2), (2, 3), (3, 4)])
m = map(_ + _ - _, [(1, 2, 3), (2, 3, 4), (3, 4, 5)])
print(list(m))