OCaml: Add implIntf

*This is the first of a series of PR I aim to do to improve the ocaml-lsp
experience in lsp-mode*

This PR exposes `lsp-ocaml-find-alternate-file` that allows to find the file
interface corresponding to an implementation or the implementation corresponding
to an interface.

This function is quite simple for the moment since I first needed to make sure
that the LSP requests were working as expected.

Following PRs will add more possibilities

Author: mattiasdrp

clients/lsp-ocaml.el

@@ -61,10 +61,14 @@
 (define-obsolete-variable-alias 'lsp-merlin 'lsp-ocaml-lsp-server "lsp-mode 6.1")
 (define-obsolete-variable-alias 'lsp-merlin-command 'lsp-ocaml-lsp-server-command "lsp-mode 6.1")
 
+;;; -------------------
+;;; OCaml-lsp custom variables
+;;; -------------------
+
 (defcustom lsp-ocaml-lsp-server-command
   '("ocamllsp")
-  "Command to start ocaml-language-server."
-  :group 'lsp-ocaml
+  "Command to start ocaml-lsp-server."
+  :group 'lsp-ocaml-lsp-server
   :type '(choice
           (string :tag "Single string value")
           (repeat :tag "List of string values"
@@ -80,7 +84,7 @@
 
 (defcustom lsp-cut-signature 'space
   "If non-nil, signatures returned on hover will not be split on newline."
-  :group 'lsp-ocaml
+  :group 'lsp-ocaml-lsp-server
   :type '(choice (symbol :tag "Default behaviour" 'cut)
                  (symbol :tag "Display all the lines with spaces" 'space)))
 
@@ -130,8 +134,10 @@ An example of function using STORABLE is:
               ntype)))
       type)))
 
+;;; -------------------
 ;;; OCaml-lsp extensions interface
-;;;
+;;; -------------------
+
 ;;; The following functions are used to create an interface between custom OCaml-lsp requests and lsp-mode
 
 (defun lsp-ocaml--switch-impl-intf ()
@@ -145,12 +151,18 @@ https://github.com/ocaml/ocaml-lsp/blob/master/ocaml-lsp-server/docs/ocamllsp/sw
       uris
     (lsp--warn "Your version of ocaml-lsp doesn't support the switchImplIntf extension")))
 
-;;; OCaml-lsp utilities
+;;; -------------------
+;;; OCaml-lsp general utilities
+;;; -------------------
 
 (defun lsp-ocaml--has-one-element-p (lst)
   "Returns t if LST contains only one element."
   (and lst (= (length lst) 1)))
 
+;;; -------------------
+;;; OCaml-lsp URI utilities
+;;; -------------------
+
 (defun lsp-ocaml--load-uri (uri &optional other-window)
   "Check if URI exists and open its buffer or create a new one.
 
@@ -181,9 +193,11 @@ If OTHER-WINDOW is not nil, open the buffer in an other window."
              (selected-file (completing-read "Choose an alternate file " filenames)))
         (nth (cl-position selected-file filenames :test #'string=) uris)))))
 
+;;; -------------------
 ;;; OCaml-lsp extensions
-;;;
-;;; The following functions are interactive implementations of the custom OCaml-lsp requests
+;;; -------------------
+
+;;; The following functions are interactive implementations of the OCaml-lsp requests
 
 (defun lsp-ocaml-find-alternate-file ()
   "Return the URI corresponding to the alternate file if there's only one or prompt for a choice."