Changes for the better

* goof-impl.scm (loop/first loop/last): add ability to specify a
:default value. Added auxiliary syntax :default.
 * goof/iterators.scm (accumulating hash(q|v)ing): changed auxiliary
keyword from initial -> :initial.
 * goof.scm: export extra keywords
 * doc.html
 * doc.xml : document changes. fix bugs.

goof-impl.scm

@@ -32,11 +32,15 @@
   :when :unless :break :final :bind :do :subloop :for :acc
   ;; Auxiliary syntax for the iterators.
   :gen
+  ;; auxiliary syntax for some accumulators
+  :initial
   ;; auxiliary auxiliary syntax
   ;; for vectoring
   :length :fill
   ;;for up-from and down-to
   :to :by
+  ;; used by for/first and for/last
+  :default
   ;; Internal syntax. %acc is turned into :acc by the forify macro
   ;; it is used make it possible to report an error if :acc is used in
   ;; one of the simple macros.
@@ -491,27 +495,32 @@
              => acc
              (product-loop)))))
 
-(define sentinel (list 'unique))
-
-;; TODO: maybe have a look at the expansion of this. It seems weird.
+;; This exploits that we give the loop a name, but don't add the loop to the end of the
+;; body, thus returning whatever the last expr of body returns.
 (define-syntax loop/first
-  (syntax-rules ()
-    ((n (clauses ...) body ...)
+  (syntax-rules (:default)
+    ((n :default val (clauses ...) body ...)
      (forify (n (clauses ...) body ...)
              loop/first
-             () (clauses ... (:final #t))
-             => #f
-             body ...))))
-
-
-(define-syntax loop/last
-  (syntax-rules ()
+             () (clauses ...)
+             => val
+             body ...))
     ((n (clauses ...) body ...)
+     (loop/first :default #f (clauses ...) body ...))))
+
+
+;; unique value used for loop/last
+(define sentinel (list 'unique))
+(define-syntax loop/last
+  (syntax-rules (:default)
+    ((n :default val (clauses ...) body ...)
      (forify (n (clauses ...) body ...)
              loop-name () (clauses ... (%acc acc (folding sentinel)))
-             => (if (eq? sentinel acc) #f acc)
+             => (if (eq? sentinel acc) val acc)
              (let ((result (let () body ...)))
-               (loop-name (=> acc result)))))))
+               (loop-name (=> acc result)))))
+    ((n (clauses ...) body ...)
+     (loop/last :default #f (clauses ...) body ...))))
 
 (define-syntax loop/and
   (syntax-rules ()