[Fix #2572] Make it possible to a start a one-off ClojureScript REPL without defining a new REPL type

Author: bbatsov

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Changes
 
 * [#2711](https://github.com/clojure-emacs/cider/pull/2711): `cider-selector` has more robust handling for edge cases.
+* [#2572](https://github.com/clojure-emacs/cider/issues/2572): Make it possible to a start a one off ClojureScript REPL without defining a new REPL type.
 
 ### Bugs fixed
 

cider.el

@@ -770,15 +770,30 @@ Figwheel for details."
                       (read-from-minibuffer "Select figwheel-main build (e.g. :dev): ")))))
     (format form (cider-normalize-cljs-init-options options))))
 
+(defcustom cider-custom-cljs-repl-init-form nil
+  "The form used to start a custom ClojureScript REPL.
+When set it becomes the return value of the `cider-custom-cljs-repl-init-form'
+function, which normally prompts for the init form.
+
+This defcustom is mostly intended for use with .dir-locals.el for
+cases where it doesn't make sense to register a new ClojureScript REPL type."
+  :type 'string
+  :safe (lambda (s) (or (null s) (stringp s)))
+  :package-version '(cider . "0.23.0"))
+
 (defun cider-custom-cljs-repl-init-form ()
-  "Prompt for a form that would start a ClojureScript REPL.
+  "The form used to start a custom ClojureScript REPL.
+Defaults to the value of `cider-custom-cljs-repl-init-form'.
+If it's nil the function will prompt for a form.
 The supplied string will be wrapped in a do form if needed."
-  (let ((form (read-from-minibuffer "Please, provide a form to start a ClojureScript REPL: ")))
-    ;; TODO: We should probably make this more robust (e.g. by using a regexp or
-    ;; parsing the form).
-    (if (string-prefix-p "(do" form)
-        form
-      (format "(do %s)" form))))
+  (or
+   cider-custom-cljs-repl-init-form
+   (let ((form (read-from-minibuffer "Please, provide a form to start a ClojureScript REPL: ")))
+     ;; TODO: We should probably make this more robust (e.g. by using a regexp or
+     ;; parsing the form).
+     (if (string-prefix-p "(do" form)
+         form
+       (format "(do %s)" form)))))
 
 (defvar cider-cljs-repl-types
   '((nashorn "(do (require 'cljs.repl.nashorn) (cider.piggieback/cljs-repl (cljs.repl.nashorn/repl-env)))"

doc/modules/ROOT/pages/basics/clojurescript.adoc

@@ -113,6 +113,16 @@ You can also modify the known ClojureScript REPLs on a per-project basis using
   (cider-default-cljs-repl . super-cljs)))
 ----
 
+For one-off REPLs you can also use the custom REPL init form like this:
+
+[source,lisp]
+----
+;; modify the list of known REPLs and set some default
+((nil
+  (cider-custom-cljs-repl-init-form . "(do (foo) (bar))"
+  (cider-default-cljs-repl . custom)))
+----
+
 If you already have a Clojure REPL running and want to add a
 ClojureScript REPL, you can invoke
 `cider-jack-in-sibling-clojurescript` to add it.