wjkoh

package main

import (
	"context"
	"embed"
	"html/template"
	"log"
	"log/slog"
	"net"
	"net/http"

wjkoh

func Lines(f io.Reader) iter.Seq2[[]byte, error] {
	r := bufio.NewReader(f)
	return func(yield func([]byte, error) bool) {
		for {
			data, err := r.ReadBytes('\n')
			if errors.Is(err, io.EOF) {
				return
			}
			if !yield(data, err) {
				return

wjkoh

Core Idea:

The primary goal of this pattern is to allow the http.HandlerFunc to always have access to the latest available set of []Company data without blocking, even while a potentially long-running crawlCompanies function is fetching new data in the background. It provides a form of non-blocking data exchange between a background worker and a request handler.

How it Works:

1. Two Buffered Channels (ch1, ch2):
   • Two channels (ch1, ch2) are created, each capable of holding exactly one []Company slice (make(chan []Company, 1)). The buffer size of 1 is key.
   • They are initialized by sending nil into each (ch1 <- nil, ch2 <- nil). This means both channels start "full" with a placeholder value.

wjkoh

package main

import (
	"context"
	"database/sql"
	"log"
	"os"

	_ "github.com/mattn/go-sqlite3"
)

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func Limit[E any](seq iter.Seq[E], limit int) iter.Seq[E] {
	return func(yield func(E) bool) {
		var count int
		for e := range seq {
			if count >= limit {
				return
			}
			if !yield(e) {
				return
			}

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type Person struct {
	Email string
	Name  string
}

type Resume struct {
	Author      *Person
	Content     string
}

wjkoh

package main

import (
	"context"
	"io"
	"time"
)

type uploader struct{}

wjkoh

package main

import "fmt"

func main() {
	fmt.Println(max(threeInts()))
}

func threeInts() (int, int, int) {
	return 32, 8, 64

wjkoh

In Go's html/template, you don't have to enclose a template action within double quotes. The html/template package automatically adds double quotes to your string.

<span title="{{.Title}}">Hello World</span>
<span title={{.Title}}>Hello World</span>

Both examples produce the same HTML:

<span title="This is title">Hello World</span>

wjkoh

package cache

import (
	"sync"
	"time"
)

type Cache[K comparable, V any] interface {
	Set(K, V)
	Get(K) (V, bool)