Polishing the README and iterator protocol.

* README.md: added some small documentation and loop expansion.
 * goof.scm: Changed the iterator protocol to not use unnecessary :acc and :fors.
 * iterators.scm: see above.
 * ref-let.scm: a new macro to allow multiple values and pattern matching to co-exist for body-bindings.

ref-let.scm

@@ -0,0 +1,51 @@
+(define-module (ref-let)
+  #:export (ref-let)
+  #:use-module (ice-9 match)
+  #:use-module (srfi srfi-71))
+
+(define-syntax ref-let
+  (syntax-rules ()
+    ((ref-let ids body ...)
+     (rl () () ids body ...))))
+
+(define-syntax rl
+  (syntax-rules (values)
+    ;; emit simple case, no match
+    ((_ (lets ...) () () body ...)
+     (let (lets ...)
+       body ...))
+    ;; emit, hard case.
+    ((rl (lets ...) (matches ...) () body ...)
+     (let (lets ...)
+       (match-let (matches ...)
+         body ...)))
+
+
+    ;; a (values ...) clause:
+    ((rl (l ...) m (((values . v) expr) . clause-rest) . body)
+     (rl (l ... ((values . v) expr)) m clause-rest . body))
+    
+    ;; Simple cases
+    ;; (rl ((a 5)) () (((b . _) (cons 1 2))) (+ a b))
+    ((_ (l ...) (m ...) (((p . p-rest) expr) . clause-rest) body ...)
+     (rl (l ... (dummy expr)) (m ... ((p . p-rest) dummy)) clause-rest body ...))
+
+    
+    ((rl (l ...) (m ...) ((binding expr) . clause-rest) body ...)
+     (rl (l ... (binding expr)) (m ...) clause-rest body ...))
+
+    ;; More than one id
+    ((rl l m ((id id* ... expr) . clause-rest) . body)
+     (extract () () (id id* ... expr) l m clause-rest . body))))
+
+(define-syntax extract
+  (syntax-rules ()
+    ((_ let-binding (match-bindings ...) () (l ...) (m ...) clauses . body)
+     (rl (l ... let-binding) (m ... match-bindings ...) clauses . body))
+    ((_ (lb ...) mb (expr) . rest)
+     (extract (lb ... expr) mb () . rest))
+    ;; Pattern
+    ((_ (lb ...) (mb ...) ((p . p-rest) ids ...) . rest)
+     (extract (lb ... dummy) (mb ... ((p . p-rest) dummy)) (ids ...) . rest))
+    ((_ (lb ...) mb (id ids ...) . rest)
+     (extract (lb ... id) mb (ids ...) . rest))))