M. J. Fromberger creachadair

Checking Type Parameters for Optional Interface Satisfaction

With Go generics, it is not permitted to check whether a value whose type comes from a type parameter satisfies some optional interface. For example, the following code will not compile (as of Go 1.20):

type Q interface{ Q() }

func G[T any](t T) {
	if q, ok := t.(Q); ok {
 q.Q()

Go library: https://pkg.go.dev/github.com/icza/mjpeg

Wikipedia: https://en.wikipedia.org/wiki/Motion_JPEG

Thinking maybe read the frames from the GIF and render them to MJPEG.

Use of Underlying Types in Go Generics

When specifying the type parameters for a generic structure in Go, you can use the notation ~T to mean "any type whose underlying structure is equivalent to T". For example, given:

func F[X ~string](x X) {}

the type parameter X can be instantiated with any type whose underlying representation is string. That includes string itself, of course, along with types like type Foo string which are based on it.

Links to various Go playground examples

Waiting for a Value to Change in Go

When multiple goroutines share access to a value that will periodically change, readers may wish to wait for a value to be updated before reading the value again. This can be solved using a condition variable:

var val *Thing
var mu = new(sync.Mutex)
var cond = sync.NewCond(mu)

func wait(old *Thing) *Thing {

Insert Text at Cursor on macOS

Requirement: Enable Accessibility for the Terminal application.

tell application "System Events"
   keystroke "text to be inserted\n"
end tell

Hugo, Nebula and Clarke Winners Checklist

Extracted from the Google form posted in https://twitter.com/hammard_1987/status/1449453485343318025.

Children of Time (Adrian Tchaikovsky)
Rite of Passage (Alexei Panshin)
The Demolished Man (Alfred Bester)
The Calcutta Chromosome (Amitav Ghosh)
Ancillary Justice (Ann Leckie)
Dreams Before the Start of Time (Anne Charnock)

	package main_test

	import (
	"fmt"
	"testing"
	)

	func BenchmarkBuf(b *testing.B) {
	for _, bs := range []int{0, 1, 2, 10, 32} {
	b.Run(fmt.Sprint(bs), func(b *testing.B) {

	#!/bin/zsh
	set -euo pipefail

	readonly pollsec=5

	if [[ "$#" = 0 ]] ; then
	echo "Missing required run ID" 1>&2
	exit 2
	fi