Trouble with ocp-indent in spacemacs on mac

Question

I'm having trouble setting up spacemacs for ocaml on my mac. Specifically, spacemacs can't seem to find ocp-indent. Whenever I enter a new line, I get the following message: "Searching for program: No such file or directory, ocp-indent"

I confirmed that I have it installed, and there's a ocp-indent directory in my elpa directory. Merlin and utop, which I believe I installed the same way with opam, both seem to work in spacemacs.

Does anyone know how I can fix this, or at least debug the problem better?

Here is spacemacs' debugger output:

Debugger entered--Lisp error: (file-error "Searching for program" "No such file or directory" "ocp-indent")
  call-process-region(1 38 "ocp-indent" "/var/folders/vz/q3dgx5jj3y1989n9y7np1h8w0000gn/T/emacsCIYxzp" (#<buffer  *string-output*> "/var/folders/vz/q3dgx5jj3y1989n9y7np1h8w0000gn/T/ocp-indent-error97945Cyf") nil "--numeric" "--lines" "4-4")
  apply(call-process-region 1 38 "ocp-indent" nil (#<buffer  *string-output*> "/var/folders/vz/q3dgx5jj3y1989n9y7np1h8w0000gn/T/ocp-indent-error97945Cyf") nil ("--numeric" "--lines" "4-4"))
  (/= 0 (apply (quote call-process-region) (point-min) (point-max) ocp-indent-path nil (list standard-output errfile) nil (ocp-indent-args start-line end-line)))
  (if (/= 0 (apply (quote call-process-region) (point-min) (point-max) ocp-indent-path nil (list standard-output errfile) nil (ocp-indent-args start-line end-line))) (error "Can't indent: %s returned failure" ocp-indent-path))
  (let ((standard-output standard-output)) (if (/= 0 (apply (quote call-process-region) (point-min) (point-max) ocp-indent-path nil (list standard-output errfile) nil (ocp-indent-args start-line end-line))) (error "Can't indent: %s returned failure" ocp-indent-path)))
  (progn (let ((standard-output standard-output)) (if (/= 0 (apply (quote call-process-region) (point-min) (point-max) ocp-indent-path nil (list standard-output errfile) nil (ocp-indent-args start-line end-line))) (error "Can't indent: %s returned failure" ocp-indent-path))) (save-current-buffer (set-buffer standard-output) (buffer-string)))
  (unwind-protect (progn (let ((standard-output standard-output)) (if (/= 0 (apply (quote call-process-region) (point-min) (point-max) ocp-indent-path nil (list standard-output errfile) nil (ocp-indent-args start-line end-line))) (error "Can't indent: %s returned failure" ocp-indent-path))) (save-current-buffer (set-buffer standard-output) (buffer-string))) (kill-buffer standard-output))
  (let ((standard-output (get-buffer-create (generate-new-buffer-name " *string-output*")))) (unwind-protect (progn (let ((standard-output standard-output)) (if (/= 0 (apply (quote call-process-region) (point-min) (point-max) ocp-indent-path nil (list standard-output errfile) nil (ocp-indent-args start-line end-line))) (error "Can't indent: %s returned failure" ocp-indent-path))) (save-current-buffer (set-buffer standard-output) (buffer-string))) (kill-buffer standard-output)))
  (let* ((start-line (line-number-at-pos start)) (end-line (line-number-at-pos end)) (errfile (expand-file-name (make-temp-name "ocp-indent-error") temporary-file-directory)) (indents-str (let ((standard-output (get-buffer-create (generate-new-buffer-name " *string-output*")))) (unwind-protect (progn (let (...) (if ... ...)) (save-current-buffer (set-buffer standard-output) (buffer-string))) (kill-buffer standard-output)))) (indents (mapcar (quote string-to-number) (split-string indents-str)))) (if (file-exists-p errfile) (progn (message (ocp-indent-file-to-string errfile)) (delete-file errfile))) (save-excursion (goto-char start) (mapcar (function (lambda (indent) (indent-line-to indent) (forward-line))) indents)) (if (ocp-in-indentation-p) (progn (back-to-indentation))))
  ocp-indent-region(37 37)
  ocp-indent-line()
  indent-according-to-mode()
  electric-indent-post-self-insert-function()
  self-insert-command(1)
  newline(nil t)
  #[0 "\300\301!\210\302\303\301\"\210\304 \207" [delete-horizontal-space t newline nil indent-according-to-mode] 3 2329134 "*"]()
  ad-Advice-newline-and-indent(#[0 "\300\301!\210\302\303\301\"\210\304 \207" [delete-horizontal-space t newline nil indent-according-to-mode] 3 2329134 "*"])
  apply(ad-Advice-newline-and-indent #[0 "\300\301!\210\302\303\301\"\210\304 \207" [delete-horizontal-space t newline nil indent-according-to-mode] 3 2329134 "*"] nil)
  newline-and-indent()
  tuareg-newline-and-indent()
  funcall-interactively(tuareg-newline-and-indent)
  call-interactively(tuareg-newline-and-indent nil nil)
  command-execute(tuareg-newline-and-indent)

Answer 1

From what you say, it seems that you do have the ocp-indent Elisp package installed, but the error message says that this ocp-indent package can't find the ocp-indent program (which is not specific to Emacs, so the ocp-indent package expects to find it somewhere along your $PATH).