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+;;;; macros.lisp --- utility macros
+
+
+(in-package :lazybones)
+
+(defmacro let-parameters ((&rest names) &body body)
+  "NAMES is a list of symbols. Binds the names to the value of the
+request parameters whose keys compare string-equal to the symbol-name
+of each NAME, or NIL if there is no such parameter."
+  (let ((params (gensym)))
+    `(let ((,params (lazybones:request-parameters)))
+      (let ,(loop for name in names
+                  for string-name = (symbol-name name) 
+                  collect `(,name (cdr (assoc ,string-name ,params :test #'string-equal))))
+        ,@body))))
+
+(defmacro map-parameters ((&rest params) &body body)
+  "PARAMS is a list of pairs (NAME PARSER).  MAP-PARAMETERS behaves
+exactly like LET-PARAMETERS except that the values boudn to NAMEs are
+first mapped with the PARSER function."
+  (assert (loop for (name parser) in params
+                always (and (symbolp name)
+                            (or (symbolp parser) (functionp parser))))
+          ()
+          "Malformed PARAMS in MAP-PARAMETERS macro")
+
+  (let ((names (mapcar #'car params)))
+    `(let-parameters ,names
+       (let ,(loop for name in names
+                   collect `(,name (when ,name (funcall ',(second (assoc name params)) ,name))))
+         ,@body))))
+