Add Atom feed examples

Author: devlights

examples/singleapp/atom/.gitignore

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+atom*

examples/singleapp/atom/Taskfile.yml

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+version: '3'
+
+tasks:
+  default:
+    cmds:
+      - task: run
+  install-lib:
+    cmds:
+      - go install golang.org/x/tools/cmd/goimports@latest
+      - go install honnef.co/go/tools/cmd/staticcheck@latest
+  build:
+    deps: [ install-lib ]
+    cmds:
+      - goimports -w .
+      - go vet
+      - staticcheck
+      - go build
+  run:
+    deps: [ build ]
+    cmds:
+      - ./atom

examples/singleapp/atom/main.go

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+package main
+
+import (
+	"encoding/xml"
+	"fmt"
+	"io"
+	"net/http"
+)
+
+type (
+	Feed struct {
+		XMLName xml.Name `xml:"feed"`
+		Titles  []string `xml:"entry>title"`
+	}
+)
+
+const (
+	URL = "https://devlights.hatenablog.com/feed"
+)
+
+func panicOnErr[T any](v T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+
+	return v
+}
+
+// ブログ [いろいろ備忘録日記](https://devlights.hatenablog.com/) から Atom Feed を取得して表示するサンプルです。
+//
+// REFERENCES:
+//   - https://qiita.com/you8/items/e903fd463cf770688e1e
+func main() {
+	fmt.Printf("[URL] %s\n", URL)
+
+	resp := panicOnErr(http.Get(URL))
+	body := panicOnErr(io.ReadAll(resp.Body))
+	defer resp.Body.Close()
+
+	var feed Feed
+	if err := xml.Unmarshal(body, &feed); err != nil {
+		panic(err)
+	}
+
+	for i, title := range feed.Titles {
+		fmt.Printf("[%2d] %s\n", i+1, title)
+	}
+}