@@ -115,11 +115,16 @@

     (<= (length it)

         len)))

-(defun applicable-when (fun test)

-  (lambda (it)

-    (if (funcall test it)

-        (funcall fun it)

-        it)))

+(defun applicable-when (fun test &optional (default nil default-p))

+  (if default-p

+      (lambda (it)

+        (if (funcall test it)

+            (funcall fun it)

+            default))

+      (lambda (it)

+        (if (funcall test it)

+            (funcall fun it)

+            it))))

 (defmacro conj (&rest fns)

   (let ((dat (gensym "dat")))

@@ -84,6 +84,9 @@

   (5am:is (equal 1

                  (funcall (data-lens:applicable-when '1+ (constantly nil))

                           1)))

+  (5am:is (equal "hi"

+                 (funcall (data-lens:applicable-when '1+ (constantly nil) "hi")

+                          1)))

   (5am:is (equal 2

                  (funcall (data-lens:applicable-when '1+ (constantly t))

                           1))))