all: upgrade and move from go2go to gotip

Author: changkun

README.md

@@ -1,34 +1,28 @@
-# go2generics
+# go2generics [![PkgGoDev](https://pkg.go.dev/badge/golang.design/x/go2generics)](https://pkg.go.dev/golang.design/x/go2generics) ![](https://changkun.de/urlstat?mode=github&repo=golang-design/go2generics)
 
-This repository demonstrates a big chunk of demos and researches about Go 2 generics.
+A chunk of demos and research regarding Go 2 generics (type parameters).
 
 ## Getting started
 
 There are several documents for you to getting familiar with generics:
 
 - [A Summary of Go Generics Research](./generics.md)
-- Changkun Ou. Go 2 Generics: Constrained Type Parameters. https://changkun.de/s/go2generics/.
+- Changkun Ou. Go 2 Generics: Type Parameters. https://changkun.de/s/go2generics/.
 
 ## Code examples
 
-You can use `go2go` to build all code examples in this repository.
+You can use the latest Go tip version to build all code examples in this repository.
 
-### Using `go2go`
+```sh
+$ git clone https://github.com/golang/go && cd src && ./all.bash
 
-1. Clone `go` repository
-
-2. Checkout `go2go` branch and build the go toolchain
-
-3. Place the repository in `GO2PATH`. The `go2generics` repository path should looks like the follows:
-
-```
-$GO2PATH/src/github.com/changkun/go2generics
+$ ../bin/go test -gcflags=all=-G=3 -v ./...
 ```
 
-Use `go tool go2go` for executing and testing the demos.
+The `-gcflags=all=-G=3` is the key compiler flag to run Go code with type parameters.
 
 ## Licnese
 
-BSD-2-Clause 
+BSD-2-Clause
 
-2020 © [Changkun Ou](https://changkun.de)
+Copyright © 2020-2021 [Changkun Ou](https://changkun.de)

chans/chans.go

@@ -1,32 +1,66 @@
-// Code generated by go2go; DO NOT EDIT.
+// Copyright 2020 Changkun Ou. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
 
-
-//line chans.go2:5
 package chans
 
-//line chans.go2:5
-import (
-//line chans.go2:5
- "math/rand"
-//line chans.go2:5
- "runtime"
-//line chans.go2:5
- "sync"
-//line chans.go2:5
- "testing"
-//line chans.go2:5
-)
-
-//line chans.go2:5
-type Importable୦ int
-
-//line chans.go2:5
-var _ = rand.ExpFloat64
-//line chans.go2:5
-var _ = runtime.BlockProfile
-
-//line chans.go2:5
-type _ sync.Cond
-
-//line chans.go2:5
-var _ = testing.AllocsPerRun
+import "runtime"
+
+// Ranger returns a Sender and a Receiver. The Receiver provides a
+// Next method to retrieve values. The Sender provides a Send method
+// to send values and a Close method to stop sending values. The Next
+// method indicates when the Sender has been closed, and the Send
+// method indicates when the Receiver has been freed.
+//
+// This is a convenient way to exit a goroutine sending values when
+// the receiver stops reading them.
+func Ranger[T any]() (*Sender[T], *Receiver[T]) {
+	c := make(chan T)
+	d := make(chan bool)
+	s := &Sender[T]{values: c, done: d}
+	r := &Receiver[T]{values: c, done: d}
+	runtime.SetFinalizer(r, r.finalize)
+	return s, r
+}
+
+// A sender is used to send values to a Receiver.
+type Sender[T any] struct {
+	values chan<- T
+	done <-chan bool
+}
+
+// Send sends a value to the receiver. It returns whether any more
+// values may be sent; if it returns false the value was not sent.
+func (s *Sender[T]) Send(v T) bool {
+	select {
+	case s.values <- v:
+		return true
+	case <-s.done:
+		return false
+	}
+}
+
+// Close tells the receiver that no more values will arrive.
+// After Close is called, the Sender may no longer be used.
+func (s *Sender[T]) Close() {
+	close(s.values)
+}
+
+// A Receiver receives values from a Sender.
+type Receiver[T any] struct {
+	values <-chan T
+	done chan<- bool
+}
+
+// Next returns the next value from the channel. The bool result
+// indicates whether the value is valid, or whether the Sender has
+// been closed and no more values will be received.
+func (r *Receiver[T]) Next() (T, bool) {
+	v, ok := <-r.values
+	return v, ok
+}
+
+// finalize is a finalizer for the receiver.
+func (r *Receiver[T]) finalize() {
+	close(r.done)
+}

chans/chans.go2

@@ -1,29 +1,46 @@
-// Code generated by go2go; DO NOT EDIT.
+// Copyright 2020 Changkun Ou. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
 
-
-//line lb.go2:5
 package chans
 
-//line lb.go2:5
 import (
-//line lb.go2:5
- "math/rand"
-//line lb.go2:5
- "runtime"
-//line lb.go2:5
- "sync"
-//line lb.go2:5
- "testing"
-//line lb.go2:5
+	"sync"
+	"math/rand"
 )
 
-//line lb.go2:5
-var _ = rand.ExpFloat64
-//line lb.go2:5
-var _ = runtime.BlockProfile
+// Fanin implements a generic fan-in for variadic channels.
+func Fanin[T any](chans ...<-chan T) <-chan T {
+	buf := 0
+	for _, ch := range chans {
+		if len(ch) > buf { buf = len(ch) }
+	}
+	out := make(chan T, buf)
+	wg := sync.WaitGroup{}
+	wg.Add(len(chans))
+	for _, ch := range chans {
+		go func(ch <-chan T) {
+			for v := range ch { out <- v }
+			wg.Done()
+		}(ch)
+	}
+	go func() {
+		wg.Wait()
+		close(out)
+	}()
+	return out
+}
 
-//line lb.go2:5
-type _ sync.Cond
+// Fanout implements a generic fan-out for variadic channels
+func Fanout[T any](randomizer func(max int) int, In <-chan T, Outs ...chan T) {
+	l := len(Outs)
+	for v := range In {
+		i := randomizer(l)
+		if i < 0 || i > l { i = rand.Intn(l) }
+		go func(v T) { Outs[i] <- v }(v)
+	}
+}
 
-//line lb.go2:5
-var _ = testing.AllocsPerRun
+func LB[T any](randomizer func(max int) int, ins []<-chan T, outs []chan T) {
+	Fanout(randomizer, Fanin(ins...), outs...)
+}