Just another update

Task/S-Expressions/Perl-6/s-expressions.pl6

@@ -1,7 +1,7 @@
 grammar S-Exp {
   rule TOP    {^ <s-list> $};
 
-  token s-list { '(' ~ ')' [ <in_list> ** [\s+] | '' ] }
+  token s-list { '(' ~ ')' [ <in_list>+ % [\s+] | '' ] }
   token in_list { <s-token> | <s-list> }
 
   proto token s-token {*}

Task/S-Expressions/Ruby/s-expressions.rb

@@ -62,14 +62,12 @@ class SExpr
   end
 
   def symbol_or_number(word)
+    Integer(word)
+  rescue ArgumentError
     begin
-      Integer(word)
+      Float(word)
     rescue ArgumentError
-      begin
-        Float(word)
-      rescue ArgumentError
-        word.to_sym
-      end
+      word.to_sym
     end
   end
 
@@ -120,5 +118,5 @@ sexpr = SExpr.new <<END
 END
 
 puts "original sexpr:\n#{sexpr.original}"
-puts "\nruby data structure:\n#{sexpr.data.inspect}"
+puts "\nruby data structure:\n#{sexpr.data}"
 puts "\nand back to S-Expr:\n#{sexpr.to_sexpr}"

Task/S-Expressions/Scheme/s-expressions.ss

@@ -1,9 +1,44 @@
-(define input "((data \"quoted data\" 123 4.5)
- (data (!@# (4.5) \"(more\" \"data)\")))")
-(define data (read (open-input-string input)))
-(define output (let ((out (open-output-string)))
-                  (write data out)
-                  (get-output-string out)))
-(write input) (newline)
-(write data) (newline)
-(write output) (newline)
+(define (sexpr-read port)
+  (define (help port)
+    (let ((char (read-char port)))
+      (cond
+       ((or (eof-object? char) (eq? char #\) )) '())
+       ((eq? char #\( ) (cons (help port) (help port)))
+       ((char-whitespace? char) (help port))
+       ((eq? char #\"") (cons (quote-read port) (help port)))
+       (#t (unread-char char port) (cons (string-read port) (help port))))))
+  ; This is needed because the function conses all parsed sexprs onto something,
+  ; so the top expression is one level too deep.
+  (car (help port)))
+
+(define (quote-read port)
+  (define (help port)
+    (let ((char (read-char port)))
+      (if
+       (or (eof-object? char) (eq? char #\""))
+       '()
+       (cons char (help port)))))
+  (list->string (help port)))
+
+(define (string-read port)
+  (define (help port)
+    (let ((char (read-char port)))
+      (cond
+       ((or (eof-object? char) (char-whitespace? char)) '())
+       ((eq? char #\) ) (unread-char char port) '())
+       (#t (cons char (help port))))))
+  (list->string (help port)))
+
+(define (format-sexpr expr)
+  (define (help expr pad)
+    (if
+     (list? expr)
+     (begin
+      (format #t "~a(~%" (make-string pad #\tab))
+      (for-each (lambda (x) (help x (1+ pad))) expr)
+      (format #t "~a)~%" (make-string pad #\tab)))
+     (format #t "~a~a~%" (make-string pad #\tab) expr)))
+  (help expr 0))
+
+(format-sexpr (sexpr-read
+ (open-input-string "((data \"quoted data\" 123 4.5) (data (!@# (4.5) \"(more\" \"data)\")))")))