first draft if

janet/recursive.janet

@@ -85,6 +85,9 @@
 (defn- expect [parser type]
  (if-not (check parser type) (expected parser type)))
 
+(defn- expect-ret [parser type]
+ (try (expect parser type) ([e] e)))
+
 # atoms
 (defn- bool [parser]
  (expect parser :bool)
@@ -261,6 +264,30 @@
  (advance parser)
  ast)
 
+### conditional forms
+(defn- iff [parser]
+ (def ast {:type :if :data @[] :token (current parser)})
+ (advance parser) #consume the if
+ (update ast array/push :data (simple parser))
+ (when-let [err (expect-ret parser :then)] (update ast array/push :data err))
+ (update ast array/push :data (nonbinding parser))
+ (when-let [err (expect-ret parser :else)] (update ast array/push :data err))
+ (update ast array/push :data (nonbinding parser))
+ ast)
+
+(defn- condd [parser])
+
+(defn- match [parser])
+
+### function forms
+(defn- fnn [parser])
+
+(defn- lambda [parser])
+
+### compoound forms
+(defn- block [parser])
+
+(defn- doo [parser])
 
 ### expressions
 # four levels of expression complexity:
@@ -315,7 +342,7 @@
   :word (word parser)
 
   # conditional forms
-  :if (unreachable)
+  :if (iff parser)
   :cond (unreachable)
   :match (unreachable)
   :with (unreachable)