Itertools

Itertools is a Go package that provides many of the same high-order functions from the Python standard library.

Next, we see the different types of high-order functions provided by Itertools. High-order functions provide the vocabulary for the declarative coding style.

Infinite iterator creators:

• Count(i): Infinite count from i
• Cycle(iter): Infinite cycling of iter (requires memory)
• Repeat(element [, n]): Repeat the element n times (or infinitely)

Iterator destroyers:

• Reduce(iter, reducer, memo): Reduce (or Foldl) across the iterator
• List(iter): Create a list from the iterator

Iterator modifiers:

• Chain(iters...): Chain together multiple iterators.
• DropWhile(predicate, iter): Drop elements until predicate(el) == false.
• TakeWhile(predicate, iter): Take elements until predicate(el) == false.
• Filter(predicate, iter): Filter out elements when predicate(el) == false.
• FilterFalse(predicate, iter): Filter out elements when predicate(el) == true.
• Slice(iter, start[, stop[, step]]): Drop elements until the start (zero-based index). Stop upon stop (exclusive) unless not given. Step is 1 unless given.

More iterator modifiers:

• Map(mapper func(interface{}) interface{}, iter): Map each element to mapper(el).
• MultiMap(multiMapper func(interface{}...)interface{}, iters...): Map all the iterators as variadic arguments to multiMaper(elements...); stop at the shortest iterator.
• MultiMapLongest(multiMapper func(interface{}...)interface{}, iters...): Same as MultiMap, except that here you need to stop at the longest iterator. Shorter iterators are filled with nil after they are exhausted.
• Starmap(multiMapper func(interface{}...)interface{}, iter): If iter is an iterator of []interface{}, then expand it to multiMapper.
• Zip(iters...): Zip multiple iterators together.
• ZipLongest(iters...): Zip multiple iterators together. Take the longest; shorter ones are appended with nil.
• Tee(iter, n): Split an iterator into n equal versions.
• Tee2(iter): Split an iterator into two equal versions.