title: cannot find package "github.com/gorilla/mux" in any of:
body: <p>I use command <code>go get github.com/gorilla/mux</code>. I made http server using Golang, and I run this program : </p>
  
  <pre><code>package main
  
  import (
      "fmt"
      "html"
      "log"
      "net/http"
  
      "github.com/gorilla/mux"
  )
  
  func main() {
  
      router := mux.NewRouter().StrictSlash(true)
      router.HandleFunc("/", Index)
      log.Fatal(http.ListenAndServe(":8080", router))
  }
  
  func Index(w http.ResponseWriter, r *http.Request) {
      fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
  </code></pre>
  
  <p>But I conflict this error : </p>
  
  <pre><code>/usr/local/go/bin/go build -i [/Users/imac/go/src]
  http.go:9:5: cannot find package "github.com/gorilla/mux" in any of:
      /usr/local/go/src/github.com/gorilla/mux (from $GOROOT)
      ($GOPATH not set)
  Error: process exited with code 1.
  </code></pre>
  
  <p>My Go environment is here : </p>
  
  <pre><code>GOARCH="amd64"
  GOBIN=""
  GOEXE=""
  GOHOSTARCH="amd64"
  GOHOSTOS="darwin"
  GOOS="darwin"
  GOPATH="/Users/imac/go"
  GORACE=""
  GOROOT="/usr/local/go"
  GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
  CC="clang"
  GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/v9/fkc_t97s5v1g9sr938zzvxvh0000gn/T/go-build096571864=/tmp/go-build -gno-record-gcc-switches -fno-common"
  CXX="clang++"
  CGO_ENABLED="1"
  </code></pre>
  
  <p>I fight with this error for a week, But I can't find out solution. Please help me.</p>