functools

Higher-order functions and operations on callable objects, similar to Python's functools module.

import functools

Functions

functools.reduce(func: Func[T, T, T], iterable: Iterable[T]) -> T

Apply a function of two arguments cumulatively to the items of iterable, from left to right, so as to reduce the iterable to a single value.

Parameters:

• func (Func[T, T, T]) -- A function of two arguments.
• iterable (Iterable[T]) -- The iterable to reduce.

Returns: The single result of the cumulative application.

functools.reduce(lambda x, y: x + y, [1, 2, 3, 4, 5])    # 15

Raises:

• TypeError -- Thrown if the iterable is empty.

functools.reduce(func: Func[T, T, T], iterable: Iterable[T], initial: T) -> T

Apply a function of two arguments cumulatively to the items of iterable, from left to right, starting with initial, so as to reduce the iterable to a single value.

Parameters:

• func (Func[T, T, T]) -- A function of two arguments.
• iterable (Iterable[T]) -- The iterable to reduce.
• initial (T) -- The initial (seed) value.

Returns: The single result of the cumulative application.

functools.reduce(lambda x, y: x + y, [1, 2, 3, 4, 5], 10)    # 25

functools.cmp_to_key(func: Func[T, T, int]) -> IComparer[T]

Convert a comparison function into a key function suitable for use with sorting. Returns an IComparer{T} that wraps the comparison function.

Parameters:

• func (Func[T, T, int]) -- A comparison function that returns a negative number for less-than, zero for equal, or a positive number for greater-than.

Returns: An IComparer{T} wrapping the comparison function.

comparer = functools.cmp_to_key(lambda a, b: a - b)
sorted([3, 1, 2], key=comparer)    # [1, 2, 3]