itertools

Go Iteration tools with a rusty flavour

Requirements

• Go 1.18+

Motivation

1. I missed some iteration style tools in Rust.
2. Wanted to see how far I could push Go generics(turns out it is very limited).
3. For fun.

Example Usage (Simple)

package main

import (
	"fmt"
	"github.com/go-playground/itertools"
)

func main() {
	results := itertools.WrapSlice([]int{4, 3, 2, 1, 0}).Iter().Filter(func(v int) bool {
		if v >= 5 {
			return true
		}
		return false
	}).Collect()

	fmt.Printf("%#v\n", results)
}

Example Usage (Complex)

See examples for more complex usages.

package main

import (
	"fmt"
	"github.com/go-playground/itertools"
	optionext "github.com/go-playground/pkg/v5/values/option"
	"strconv"
)

type FakeIterator struct {
	max int
}

func (f *FakeIterator) Next() optionext.Option[int] {
	f.max--
	if f.max < 0 {
		return optionext.None[int]()
	}
	return optionext.Some(f.max)
}

func main() {
	results := itertools.WrapSliceMap[int, string]([]int{4, 3, 2, 1, 0}).Iter().Chain(&FakeIterator{
		max: 10,
	}).Filter(func(v int) bool {
		if v >= 5 {
			return true
		}
		return false
	}).StepBy(2).Take(6).Map(func(v int) string {
		return strconv.Itoa(v)
	}).Iter().Collect()

	fmt.Printf("%#v\n", results)
}

Caveats

• Map and it's MAP type parameter must be defined and passed around to be able to using inline. This is a limitation of Go generics not allowing new type parameters on methods.
• Chunk can only be used at the end of a series of iterators from Iter but can be used and wrapped by Iter again. This is a limitation of the Go Compiler which causes a recursive initialization issue https://github.com/golang/go/issues/50215.
• Iter must be called on some types, like the wrapped slice or map types, to allow usage of helper functions tied directly to them but not Iterate
• Reduce will have to be used directly instead of other helper function such as Sum, Product, ... again because no new type parameters on methods.

How to Contribute

Make a pull request... can't guarantee it will be added, going to strictly vet what goes in.

License

Distributed under MIT License, please see license file within the code for more details.