+ (!reduce (lambda (s1 s2) (concat-two s1 s2))
+ strs
+ ""))
+
+;;; Concatenate a list of strings, with a separator
+(defun join (list separator)
+ (cond
+ ((null list)
+ "")
+ ((null (cdr list))
+ (car list))
+ (t
+ (concat (car list)
+ separator
+ (join (cdr list) separator)))))
+
+(defun join-trailing (list separator)
+ (cond
+ ((null list)
+ "")
+ ((null (car list))
+ (join-trailing (cdr list) separator))
+ (t
+ (concat (car list) separator (join-trailing (cdr list) separator)))))
+
+(defun integer-to-string (x)
+ (if (zerop x)
+ "0"
+ (let ((digits nil))
+ (while (not (= x 0))
+ (push (mod x 10) digits)
+ (setq x (truncate x 10)))
+ (join (mapcar (lambda (d) (string (char "0123456789" d)))
+ digits)
+ ""))))
+
+;;;; Reader
+
+;;; It is a basic Lisp reader. It does not use advanced stuff
+;;; intentionally, because we want to use it to bootstrap a simple
+;;; Lisp. The main entry point is the function `ls-read', which
+;;; accepts a strings as argument and return the Lisp expression.
+(defun make-string-stream (string)
+ (cons string 0))
+
+(defun %peek-char (stream)
+ (and (< (cdr stream) (length (car stream)))
+ (char (car stream) (cdr stream))))
+
+(defun %read-char (stream)
+ (and (< (cdr stream) (length (car stream)))
+ (prog1 (char (car stream) (cdr stream))
+ (setcdr stream (1+ (cdr stream))))))
+
+(defun whitespacep (ch)
+ (or (char= ch #\space) (char= ch #\newline) (char= ch #\tab)))
+
+(defun skip-whitespaces (stream)
+ (let (ch)
+ (setq ch (%peek-char stream))
+ (while (and ch (whitespacep ch))
+ (%read-char stream)
+ (setq ch (%peek-char stream)))))
+
+(defun terminalp (ch)
+ (or (null ch) (whitespacep ch) (char= #\) ch) (char= #\( ch)))
+
+(defun read-until (stream func)
+ (let ((string "")
+ (ch))
+ (setq ch (%peek-char stream))
+ (while (not (funcall func ch))
+ (setq string (concat string (string ch)))
+ (%read-char stream)
+ (setq ch (%peek-char stream)))
+ string))
+
+(defun skip-whitespaces-and-comments (stream)
+ (let (ch)
+ (skip-whitespaces stream)
+ (setq ch (%peek-char stream))
+ (while (and ch (char= ch #\;))
+ (read-until stream (lambda (x) (char= x #\newline)))
+ (skip-whitespaces stream)
+ (setq ch (%peek-char stream)))))
+
+(defun %read-list (stream)
+ (skip-whitespaces-and-comments stream)
+ (let ((ch (%peek-char stream)))
+ (cond
+ ((char= ch #\))
+ (%read-char stream)
+ nil)
+ ((char= ch #\.)
+ (%read-char stream)
+ (skip-whitespaces-and-comments stream)
+ (prog1 (ls-read stream)
+ (unless (char= (%read-char stream) #\))
+ (error "')' was expected."))))
+ (t
+ (cons (ls-read stream) (%read-list stream))))))
+
+(defun read-string (stream)
+ (let ((string "")
+ (ch nil))
+ (setq ch (%read-char stream))
+ (while (not (char= ch #\"))
+ (when (char= ch #\\)
+ (setq ch (%read-char stream)))
+ (setq string (concat string (string ch)))
+ (setq ch (%read-char stream)))
+ string))
+
+(defvar *eof* (make-symbol "EOF"))
+(defun ls-read (stream)
+ (skip-whitespaces-and-comments stream)
+ (let ((ch (%peek-char stream)))
+ (cond
+ ((null ch)
+ *eof*)
+ ((char= ch #\()
+ (%read-char stream)
+ (%read-list stream))
+ ((char= ch #\')
+ (%read-char stream)
+ (list 'quote (ls-read stream)))
+ ((char= ch #\`)
+ (%read-char stream)
+ (list 'backquote (ls-read stream)))
+ ((char= ch #\")
+ (%read-char stream)
+ (read-string stream))
+ ((char= ch #\,)
+ (%read-char stream)
+ (if (eql (%peek-char stream) #\@)
+ (progn (%read-char stream) (list 'unquote-splicing (ls-read stream)))
+ (list 'unquote (ls-read stream))))
+ ((char= ch #\#)
+ (%read-char stream)
+ (ecase (%read-char stream)
+ (#\'
+ (list 'function (ls-read stream)))
+ (#\\
+ (let ((cname
+ (concat (string (%read-char stream))
+ (read-until stream #'terminalp))))
+ (cond
+ ((string= cname "space") (char-code #\space))
+ ((string= cname "newline") (char-code #\newline))
+ (t (char-code (char cname 0))))))
+ (#\+
+ (let ((feature (read-until stream #'terminalp)))
+ (cond
+ ((string= feature "common-lisp")
+ (ls-read stream) ;ignore
+ (ls-read stream))
+ ((string= feature "lispstrack")
+ (ls-read stream))
+ (t
+ (error "Unknown reader form.")))))))
+ (t
+ (let ((string (read-until stream #'terminalp)))
+ (if (every #'digit-char-p string)
+ (parse-integer string)
+ (intern (string-upcase string))))))))
+
+(defun ls-read-from-string (string)
+ (ls-read (make-string-stream string)))
+
+
+;;;; Compiler
+
+(defvar *compilation-unit-checks* '())
+
+(defvar *env* '())
+(defvar *fenv* '())
+
+(defun make-binding (name type js declared)
+ (list name type js declared))
+
+(defun binding-name (b) (first b))
+(defun binding-type (b) (second b))
+(defun binding-translation (b) (third b))
+(defun binding-declared (b)
+ (and b (fourth b)))
+(defun mark-binding-as-declared (b)
+ (setcar (cdddr b) t))
+
+(let ((counter 0))
+ (defun gvarname (symbol)
+ (concat "v" (integer-to-string (incf counter))))
+
+ (defun lookup-variable (symbol env)
+ (or (assoc symbol env)
+ (assoc symbol *env*)
+ (let ((name (symbol-name symbol))
+ (binding (make-binding symbol 'variable (gvarname symbol) nil)))
+ (push binding *env*)
+ (push (lambda ()
+ (unless (binding-declared (assoc symbol *env*))
+ (error (concat "Undefined variable `" name "'"))))
+ *compilation-unit-checks*)
+ binding)))
+
+ (defun lookup-variable-translation (symbol env)
+ (binding-translation (lookup-variable symbol env)))
+
+ (defun extend-local-env (args env)
+ (append (mapcar (lambda (symbol)
+ (make-binding symbol 'variable (gvarname symbol) t))
+ args)
+ env)))
+
+(let ((counter 0))
+ (defun lookup-function (symbol env)
+ (or (assoc symbol env)
+ (assoc symbol *fenv*)
+ (let ((name (symbol-name symbol))
+ (binding
+ (make-binding symbol
+ 'function
+ (concat "f" (integer-to-string (incf counter)))
+ nil)))
+ (push binding *fenv*)
+ (push (lambda ()
+ (unless (binding-declared (assoc symbol *fenv*))
+ (error (concat "Undefined function `" name "'"))))
+ *compilation-unit-checks*)
+ binding)))
+
+ (defun lookup-function-translation (symbol env)
+ (binding-translation (lookup-function symbol env))))
+
+
+(defvar *toplevel-compilations* nil)
+
+(defun %compile-defvar (name)
+ (let ((b (lookup-variable name *env*)))
+ (mark-binding-as-declared b)
+ (push (concat "var " (binding-translation b)) *toplevel-compilations*)))
+
+(defun %compile-defun (name)
+ (let ((b (lookup-function name *env*)))
+ (mark-binding-as-declared b)
+ (push (concat "var " (binding-translation b)) *toplevel-compilations*)))
+
+(defun %compile-defmacro (name lambda)
+ (push (make-binding name 'macro lambda t) *fenv*))