diff --git a/beautiful-racket-lib/br/cond.rkt b/beautiful-racket-lib/br/cond.rkt
new file mode 100644
index 0000000..dd1de32
--- /dev/null
+++ b/beautiful-racket-lib/br/cond.rkt
@@ -0,0 +1,36 @@
+#lang racket/base
+(require (for-syntax racket/base))
+(provide (all-defined-out))
+
+(define-syntax-rule (until COND EXPR ...)
+  (let loop ()
+    (unless COND
+      EXPR ...
+      (loop))))
+
+(define-syntax-rule (while COND EXPR ...)
+  (let loop ()
+    (when COND
+      EXPR ...
+      (loop))))
+
+(define-syntax (forever stx)
+  (syntax-case stx ()
+    [(_ . EXPRS)
+     ;; todo: would be better with a syntax parameter
+     (with-syntax ([stop (datum->syntax #'EXPRS 'stop)])
+       #'(let/ec stop
+           (while #t
+                  . EXPRS)))]))
+
+(module+ test
+  (require rackunit)
+  (check-equal? (let ([x 5])
+                  (until (zero? x)
+                         (set! x (- x 1)))
+                  x) 0)
+  (check-equal? (let ([x 5])
+                  (while (positive? x)
+                         (set! x (- x 1)))
+                  x) 0))
+
diff --git a/beautiful-racket-lib/br/conditional.rkt b/beautiful-racket-lib/br/conditional.rkt
deleted file mode 100644
index c28b561..0000000
--- a/beautiful-racket-lib/br/conditional.rkt
+++ /dev/null
@@ -1,15 +0,0 @@
-#lang racket/base
-(require (for-syntax racket/base))
-(provide (all-defined-out))
-
-(define-syntax-rule (until cond expr ...)
-  (let loop ()
-    (unless cond
-      expr ...
-      (loop))))
-
-(define-syntax-rule (while cond expr ...)
-  (let loop ()
-    (when cond
-      expr ...
-      (loop))))
\ No newline at end of file
diff --git a/beautiful-racket-lib/br/datum.rkt b/beautiful-racket-lib/br/datum.rkt
index 66cf650..714f6f0 100644
--- a/beautiful-racket-lib/br/datum.rkt
+++ b/beautiful-racket-lib/br/datum.rkt
@@ -23,13 +23,16 @@
                                                                                    (syntax->datum arg)
                                                                                    arg)) (list <arg> ...)))))])))
 
+(define (datum? x) (or (list? x) (symbol? x)))
+
 (define (format-datum datum-template . args)
   (string->datum (apply format (format "~a" datum-template) (map (λ(arg) (if (syntax? arg)
                                                                              (syntax->datum arg)
                                                                              arg)) args))))
 
-(define (format-datums datum-template args)
-  (map (λ(arg) (format-datum datum-template arg)) args))
+;; todo: rephrase errors from `format` or `map` in terms of `format-datums`
+(define (format-datums datum-template . argss)
+  (apply map (λ args (apply format-datum datum-template args)) argss))
 
 (module+ test
   (require rackunit syntax/datum)
diff --git a/beautiful-racket-lib/br/debug.rkt b/beautiful-racket-lib/br/debug.rkt
index 3788e04..fb4dbc3 100644
--- a/beautiful-racket-lib/br/debug.rkt
+++ b/beautiful-racket-lib/br/debug.rkt
@@ -4,23 +4,24 @@
 
 (define-syntax (report stx)
   (syntax-case stx ()
-    [(_ expr) #'(report expr expr)]
-    [(_ expr name)
-     #'(let ([expr-result expr]) 
-         (eprintf "~a = ~v\n" 'name expr-result)
+    [(_ EXPR) #'(report EXPR EXPR)]
+    [(_ EXPR NAME)
+     #'(let ([expr-result EXPR]) 
+         (eprintf "~a = ~v\n" 'NAME expr-result)
          expr-result)]))
 
 (define-syntax (report-datum stx)
   (syntax-case stx ()
-    [(_ stx-expr) (with-syntax ([datum (syntax->datum #'stx-expr)])
-                    #'(report-datum stx-expr datum))]
-    [(_ stx-expr name)
+    [(_ STX-EXPR)
+     (with-syntax ([datum (syntax->datum #'STX-EXPR)])
+       #'(report-datum STX-EXPR datum))]
+    [(_ STX-EXPR NAME)
      #'(let () 
-         (eprintf "~a = ~v\n" 'name (syntax->datum stx-expr))
-         stx-expr)]))
+         (eprintf "~a = ~v\n" 'NAME (syntax->datum STX-EXPR))
+         STX-EXPR)]))
 
-(define-syntax-rule (define-multi-version multi-name name)
-  (define-syntax-rule (multi-name x (... ...))
-    (begin (name x) (... ...))))
+(define-syntax-rule (define-multi-version MULTI-NAME NAME)
+  (define-syntax-rule (MULTI-NAME x (... ...))
+    (begin (NAME x) (... ...))))
 
 (define-multi-version report* report)
\ No newline at end of file
diff --git a/beautiful-racket-lib/br/main.rkt b/beautiful-racket-lib/br/main.rkt
index 41e16fe..33255a3 100644
--- a/beautiful-racket-lib/br/main.rkt
+++ b/beautiful-racket-lib/br/main.rkt
@@ -1,10 +1,10 @@
 #lang racket/base
 (require racket/provide racket/list racket/string racket/format racket/match racket/port
-         br/define br/syntax br/datum br/debug br/conditional racket/function
+         br/define br/syntax br/datum br/debug br/cond racket/function
          (for-syntax racket/base racket/syntax br/syntax br/debug br/define))
 (provide (except-out (all-from-out racket/base) define)
          (all-from-out racket/list racket/string racket/format racket/match racket/port
-                       br/syntax br/datum br/debug br/conditional racket/function)
+                       br/syntax br/datum br/debug br/cond racket/function)
          (for-syntax (all-from-out racket/base racket/syntax br/syntax br/debug))
          (for-syntax caller-stx shared-syntax with-shared-id with-calling-site-id) ; from br/define
          (filtered-out