1. jaeyeun
  2. pypy


pypy / lib_pypy / _functools.py

""" Supplies the internal functions for functools.py in the standard library """

sentinel = object()

def reduce(func, sequence, initial=sentinel):
    """reduce(function, sequence[, initial]) -> value

Apply a function of two arguments cumulatively to the items of a sequence,
from left to right, so as to reduce the sequence to a single value.
For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates
((((1+2)+3)+4)+5).  If initial is present, it is placed before the items
of the sequence in the calculation, and serves as a default when the
sequence is empty."""
    iterator = iter(sequence)
    if initial is sentinel:
            initial = next(iterator)
        except StopIteration:
            raise TypeError("reduce() of empty sequence with no initial value")
    result = initial
    for item in iterator:
        result = func(result, item)
    return result

class partial(object):
    partial(func, *args, **keywords) - new function with partial application
    of the given arguments and keywords.

    def __init__(self, func, *args, **keywords):
        if not callable(func):
            raise TypeError("the first argument must be callable")
        self.func = func
        self.args = args
        self.keywords = keywords or None

    def __call__(self, *fargs, **fkeywords):
        if self.keywords is not None:
            fkeywords = dict(self.keywords, **fkeywords)
        return self.func(*(self.args + fargs), **fkeywords)