I’m using go-mode and needed the following script to correctly guess my GOPATH:

(defun go-set-project-with-guard ()
  (let* ((g (go-guess-gopath))
          (d (concat (getenv "HOME") "/src/golang"))
          (r (concat (getenv "HOME") "/src:"))
          (has-match (string-match r g)))

    (if (not (eq 0 has-match))
        (setenv "GOPATH" d)
        (setenv "GOPATH" g))))

(eval-after-load 'go-mode
  '(add-hook 'go-mode-hook 'go-set-project-with-guard))

The problem with using go-mode’s script was that my default path for code is ~/src. Which means that go-guess-gopath will recurse up to the top of that path rather than remaining at ~/src/golang.

So I wrapped the script with my own fn to check if script returns incorrect pathing, and set it correctly if so.

PS - I’d prefer to use apply-partially here for concat '(getenv "HOME")' but didn’t get it working in 10 min and figured my time was better spent posting this blog entry.