clisp/step0_repl.lisp

   1 (defpackage :mal
   2   (:use :common-lisp
   3         :readline))
   4
   5 (in-package :mal)
   6
   7 (defun mal-read (string)
   8   string)
   9
  10 (defun mal-eval (ast env)
  11   ast)
  12
  13 (defun mal-print (expression)
  14   expression)
  15
  16 (defun rep (string)
  17   (mal-print (mal-eval (mal-read string)
  18                        (make-hash-table :test #'equal))))
  19
  20 ;; Readline setup
  21 ;;; The test runner sets this environment variable, in which case we do
  22 ;;; use readline since tests do not work with the readline interface
  23 (defvar use-readline-p (not (string= (ext:getenv "PERL_RL") "false")))
  24
  25 (defvar *history-file* (namestring (merge-pathnames (user-homedir-pathname)
  26                                                          ".mal-clisp-history")))
  27
  28 (defun load-history ()
  29   (readline:read-history *history-file*))
  30
  31 (defun save-history ()
  32   (readline:write-history *history-file*))
  33
  34 ;; Setup history
  35 (when use-readline-p
  36   (load-history))
  37
  38 (defun raw-input (prompt)
  39   (format *standard-output* prompt)
  40   (force-output *standard-output*)
  41   (read-line *standard-input* nil))
  42
  43 (defun mal-readline (prompt)
  44   (let ((input (if use-readline-p
  45                    (readline:readline prompt)
  46                    (raw-input prompt))))
  47     (when (and use-readline-p
  48                input
  49                (not (zerop (length input))))
  50       (readline:add-history input))
  51     input))
  52
  53 (defun mal-writeline (string)
  54   (when string
  55     (write-line string)))
  56
  57 (defun main ()
  58   (loop do (let ((line (mal-readline "user> ")))
  59              (if line
  60                  (mal-writeline (rep line))
  61                  (return))))
  62   (when use-readline-p
  63     (save-history)))
  64
  65 ;; Do not start REPL inside Emacs
  66 (unless (member :swank *features*)
  67   (main))