Simple Hello World Golang Web Application

app.go

package main

import (
  "net/http"
  
  "github.com/gorilla/mux"
)

func main() {
  r := mux.NewRouter()
  r.HandleFunc("/{name[a-zA-Z]+}", RootHandler).Methods("GET") // Restricts "/:name" to only allow GETs
  http.Handle("/", r)
  http.ListenAndServe(":8080", nil)
}

func RootHandler(w http.ResponseWriter, r *http.Request) {
  params := mux.Vars(r) // Parses the variables in URLS for extraction
  name := params["name"]
  
  hello := fmt.Sprintf("Hello, %s", name);
  fmt.Fprintln(w, hello) // Prints as text/plain; More magic is needed for JSON
}

A little late to the party, but you forgot to import "fmt" 👍