# iter — Lazy Iterators with Generics for Go [](https://pkg.go.dev/github.com/enetx/iter) [](https://goreportcard.com/report/github.com/enetx/iter) [](https://coveralls.io/github/enetx/iter?branch=main) [](https://github.com/enetx/iter/actions/workflows/go.yml) [](https://deepwiki.com/enetx/iter) `iter` is a library of lazy iterators for Go. Built on pure functions, no unnecessary allocations, with full generics support and a clean functional style. Apply transformations like `Map`, `Filter`, `Take`, `Fold`, `Zip` directly to sequences — lazily and efficiently. --- ## 📦 Installation ```bash go get github.com/enetx/iter ``` --- ## 🚀 Example ```go package main import ( "fmt" "github.com/enetx/iter" ) func main() { // Extract even numbers and square them: s := iter.FromSlice([]int{1, 2, 3, 4, 5}) s = iter.Filter(s, func(x int) bool { return x%2 == 0 }) // 2, 4 s = iter.Map(s, func(x int) int { return x * x }) // 4, 16 out := iter.ToSlice(s) fmt.Println(out) // [4 16] } ``` --- ## ✨ Features - ✅ **Lazy sequences** — transformations are not applied until iteration begins. - ✅ **Generics-powered** — works with any types `T`, `U`, structs, etc. - ✅ **Zero-allocation** — avoids unnecessary memory allocations. - ✅ **Functional API** — each transformation is a pure function: `Map`, `Filter`, `Take`, `Skip`, `StepBy`, `Flatten`, `Zip`, `Enumerate`, `Fold`, `Reduce`, and many more. - ✅ **Supports pairs, maps, channels** — `Seq2`, `FromMap`, `FromChan`, and beyond. --- ## 🔬 More Examples ```go // Simple range with step r := iter.Iota(1, 10) // 1..9 r = iter.StepBy(r, 3) // 1, 4, 7 fmt.Println(iter.ToSlice(r)) // → [1 4 7] // Iterate over a map m := map[string]int{"a": 1, "b": 2} s2 := iter.FromMap(m) iter.ForEach2(s2, func(k string, v int) { fmt.Printf("%s → %d\n", k, v) }) ``` --- ## ⚖️ License MIT