Tell ensime to use dash-at-point for scala-doc lookup

dash-at-point.el

(add-to-list 'load-path "~/.emacs.d/vendor/dash-at-point/")
(require 'dash-at-point)

(defun dash-at-point/make-url (docset type member &optional delimiter)
  "Returns dash url given docset (scala, java?), an ensime type and an ensime member"
  (let ((member-suffix (if member (format "%s%s" (or delimiter ".") member) "")))
    (format "dash://%s:%s%s" docset type member-suffix)))

(defun dash-at-point/ensime-make-java-doc-url (ensime-type &optional member)
  (let* ((type (ensime-type-full-name ensime-type))
         (sanitized-type (replace-regexp-in-string "^java\\.lang\\." "" type)))
    (dash-at-point/make-url "java" 
                            sanitized-type
                            (ensime-member-name member)
                            "%20"))) ;; dash javadoc sets do not index methods with owner Class prefix

(defun dash-at-point/ensime-make-scala-doc-url (type &optional member)
  (dash-at-point/make-url "scala" 
                          (ensime-type-full-name type)
                          (ensime-member-name member)))

(defun dash-at-point/browsable-url-p  (s)
  "Returns true if a url should be opened via OS url handler"
  (cond ((not (stringp s)) nil)
        ((string-match "^file://" s) nil)
        ((string-match "^[a-z]+://" s) t)))

(defun dash-at-point/alist-replace (list name new-value)
  "Replaces value for name in list. Does not mutate original list"
  (let ((list-with-item-removed (delq (assoc name list) list)))
    (append list-with-item-removed
            (list (cons name new-value)))))

(eval-after-load 'ensime
  '(progn

     (setq ensime-doc-lookup-map
           (dash-at-point/alist-replace ensime-doc-lookup-map
                                        "^java\\."
                                        'dash-at-point/ensime-make-java-doc-url))
     (setq ensime-doc-lookup-map
           (dash-at-point/alist-replace ensime-doc-lookup-map
                                        "^scala\\." 
                                        'dash-at-point/ensime-make-scala-doc-url))

     (defun ensime-http-url-p (s)
       "Hack the ensime http predicate to treat dash urls as http, so
ensime will open said URL in the browser rather than in emacs."
       (dash-at-point/browsable-url-p (s)))))