kit

package main

import (
	"context"
	"fmt"
	"github.com/harmonikit/kit"
)

var (
	ctx = context.Background()
	req = struct{}{}
)

func main() {
	e := kit.Chain[struct{}, struct{}](
		annotate[struct{}, struct{}]("first"),
		annotate[struct{}, struct{}]("second"),
		annotate[struct{}, struct{}]("third"),
	)(myEndpoint)

	if _, err := e(ctx, req); err != nil {
		panic(err)
	}

}

func annotate[REQ any, RES any](s string) kit.Middleware[REQ, RES] {
	return func(next kit.Endpoint[REQ, RES]) kit.Endpoint[REQ, RES] {
		return func(ctx context.Context, request REQ) (RES, error) {
			fmt.Println(s, "pre")
			defer fmt.Println(s, "post")
			return next(ctx, request)
		}
	}
}

func myEndpoint(context.Context, struct{}) (struct{}, error) {
	fmt.Println("my endpoint!")
	return struct{}{}, nil
}

Output:

first pre
second pre
third pre
my endpoint!
third post
second post
first post