emacs: Add code to call guile procedures.

* emacs/guix-guile.el (guix-guile-make-call-expression): New function.
* emacs/guix-geiser.el: Require 'guix-guile'.
  (guix-geiser-call, guix-geiser-call-in-repl): New functions.

emacs/guix-geiser.el

@@ -24,6 +24,7 @@
 ;;; Code:
 
 (require 'geiser-mode)
+(require 'guix-guile)
 
 (defun guix-geiser-repl ()
   "Return the current Geiser REPL."
@@ -79,6 +80,18 @@ If NO-DISPLAY is non-nil, do not switch to the REPL buffer."
     (unless no-display
       (geiser-repl--switch-to-buffer repl))))
 
+(defun guix-geiser-call (proc &rest args)
+  "Call (PROC ARGS ...) synchronously using the current Geiser REPL.
+PROC and ARGS should be strings."
+  (guix-geiser-eval
+   (apply #'guix-guile-make-call-expression proc args)))
+
+(defun guix-geiser-call-in-repl (proc &rest args)
+  "Call (PROC ARGS ...) in the current Geiser REPL.
+PROC and ARGS should be strings."
+  (guix-geiser-eval-in-repl
+   (apply #'guix-guile-make-call-expression proc args)))
+
 (provide 'guix-geiser)
 
 ;;; guix-geiser.el ends here

emacs/guix-guile.el

@@ -24,6 +24,13 @@
 
 ;;; Code:
 
+(defun guix-guile-make-call-expression (proc &rest args)
+  "Return \"(PROC ARGS ...)\" string.
+PROC and ARGS should be strings."
+  (format "(%s %s)"
+          proc
+          (mapconcat #'identity args " ")))
+
 (defun guix-make-guile-expression (fun &rest args)
   "Return string containing a guile expression for calling FUN with ARGS."
   (format "(%S %s)" fun