interpret forward-declared functions, allowing mutual recursion

janet/interpreter.janet

@@ -362,7 +362,6 @@
   (def the-fn @{:name name :^type :fn :body clauses :ctx ctx})
   (set (ctx name) the-fn))
 
-# TODO
 (defn- is_placeholder [x] (= x :_))
 
 (var call-fn nil)
@@ -389,6 +388,8 @@
       (print "Janet function")
       (break (the-fn ;args)))
   (def clauses (the-fn :body))
+  (when (= :nothing clauses)
+    (error {:node the-fn :value args :msg "cannot call function before it is defined"}))
   (def len (length clauses))
   (when (the-fn :match) (break ((the-fn :match) 0 args)))
   (defn match-fn [i args]
@@ -552,15 +553,18 @@
   # (when (has-errors? validated) (break (validated :errors)))
   # (def cleaned (get-in parsed [:ast :data 1]))
   # (pp cleaned)
-  (interpret (parsed :ast) @{:^parent b/ctx})
-  # (try (interpret (parsed :ast) @{})
-  #   ([e] (print "Ludus panicked!: " 
-  #     (if (struct? e) (error (e :msg)) (error e)))))
+  # (interpret (parsed :ast) @{:^parent b/ctx})
+  (try (interpret (parsed :ast) @{})
+    ([e] (print "Ludus panicked!: " 
+      (if (struct? e) (error (e :msg)) (error e)))))
   )
 
 (do 
 (set source `
-let #{:a ay, :b (:ok, bee), ...c} = #{:a 1, :b (:ok, 42), :c 3}
+fn foo
+fn bar () -> foo ()
+fn foo () -> :foo
+bar ()
 `)
 (def result (run))
 # (b/show result)