import functools
import itertools
from typing import (Callable,
Iterable,
List,
Tuple)
from .hints import (Domain,
Map,
Range)
from .iterating import expand
[docs]def accumulator(function: Callable[[Range, Domain], Range],
initial: Range
) -> Map[Iterable[Domain], Iterable[Range]]:
"""
Returns function that yields cumulative results of given binary function
starting from given initial object in direction from left to right.
>>> import math
>>> to_pi_approximations = accumulator(round, math.pi)
>>> list(to_pi_approximations(range(5, 0, -1)))
[3.141592653589793, 3.14159, 3.1416, 3.142, 3.14, 3.1]
"""
return functools.partial(accumulate,
function=function,
initial=initial)
def accumulate(iterable: Iterable[Domain],
function: Callable[[Range, Domain], Range],
initial: Range) -> Iterable[Range]:
"""
Yields cumulative results of given binary function
starting from given initial object in direction from left to right.
"""
yield from itertools.accumulate(attach(iterable, initial), function)
[docs]def attacher(object_: Domain) -> Map[Iterable[Domain], Iterable[Domain]]:
"""
Returns function that prepends given object to iterable.
>>> attach_hundred = attacher(100)
>>> list(attach_hundred(range(10)))
[100, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
"""
return functools.partial(attach,
object_=object_)
[docs]@functools.singledispatch
def attach(iterable: Iterable[Domain],
object_: Domain) -> Iterable[Domain]:
"""
Prepends given object to the iterable.
"""
yield from itertools.chain(expand(object_), iterable)
@attach.register(list)
def _(iterable: List[Domain],
object_: Domain) -> List[Domain]:
"""
Prepends given object to the list.
"""
return [object_] + iterable
@attach.register(tuple)
def _(iterable: Tuple[Domain, ...],
object_: Domain) -> Tuple[Domain, ...]:
"""
Prepends given object to the tuple.
"""
return (object_,) + iterable
[docs]def folder(function: Callable[[Range, Domain], Range],
initial: Range) -> Map[Iterable[Domain], Range]:
"""
Returns function that cumulatively applies given binary function
starting from given initial object in direction from left to right.
>>> to_sum_evaluation_order = folder('({} + {})'.format, 0)
>>> to_sum_evaluation_order(range(1, 10))
'(((((((((0 + 1) + 2) + 3) + 4) + 5) + 6) + 7) + 8) + 9)'
"""
return functools.partial(fold,
function=function,
initial=initial)
def fold(iterable: Iterable[Domain],
function: Callable[[Range, Domain], Range],
initial: Range) -> Range:
"""
Cumulatively applies given binary function
starting from given initial object in direction from left to right.
"""
return functools.reduce(function, iterable, initial)
Applier = functools.partial
[docs]def applier(function: Callable[..., Range],
*args: Domain,
**kwargs: Domain) -> Callable[..., Range]:
"""
Returns function that behaves like given function
with given arguments partially applied.
Given positional arguments will be added to the left end.
>>> count_from_zero_to = applier(range, 0)
>>> list(count_from_zero_to(10))
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
"""
return Applier(function, *args, **kwargs)