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)

janet/parser.janet

@@ -786,7 +786,7 @@
    (def data (case (-> parser current type)
     :lbrace (fn-clauses parser)
     :lparen (fn-simple parser)
-    (panic parser (string "expected clause or clauses, got " (-> current parser type)))))
+    :nothing))
    @{:type :fn :name name :data data :token origin})
   ([err] err)))
 
@@ -1130,7 +1130,9 @@
 (do
 # (comment
 (def source `
-print! ("hello")
+fn foo
+fn bar
+fn () -> :baz
 `)
 (def scanned (s/scan source))
 (print "\n***NEW PARSE***\n")

janet/validate.janet

@@ -90,6 +90,9 @@ Deferred until a later iteration of Ludus:
  (set (validator :ctx) parent)
  validator)
 
+(defn- resolve-local [ctx name]
+ (get ctx name))
+
 (defn- resolve-name [ctx name]
  (when (nil? ctx) (break nil))
  (def node (get ctx name))
@@ -272,6 +275,24 @@ Deferred until a later iteration of Ludus:
  (match-clauses validator clauses)
  validator)
 
+(defn- declare [validator fnn]
+ (def status (validator :status))
+ (def declared (get status :declared @{}))
+ (set (declared fnn) true)
+ (set (status :declared) declared)
+ (print "declared function " (fnn :name))
+ (pp declared)
+ validator)
+
+(defn- define [validator fnn]
+ (def status (validator :status))
+ (def declared (get status :declared @{}))
+ (set (declared fnn) nil)
+ (set (status :declared) declared)
+ (print "defined function " (fnn :name))
+ (pp declared)
+ validator)
+
 (defn- fnn [validator]
  (def ast (validator :ast))
  (def name (ast :name))
@@ -281,18 +302,22 @@ Deferred until a later iteration of Ludus:
  (set (status :tail) true)
  (when name 
   (def ctx (validator :ctx))
-  (def resolved (resolve-name ctx name))
-  (when resolved
+  (def resolved (ctx name))
+  (when (and resolved (not= :nothing (resolved :data)))
    (def {:line line :input input} (get-in ctx [name :token]))
    (array/push (validator :errors)
     {:node ast :msg (string "name is already bound on line " line " of " input)}))
+  (when (and resolved (= :nothing (resolved :data)))
+   (define validator resolved))
   (set (ctx name) ast))
- (match-clauses validator (ast :data))
+ (def data (ast :data))
+ (when (= data :nothing)
+  (break (declare validator ast)))
+ (match-clauses validator data)
  (set (status :tail) tail?)
- (def clauses (ast :data))
  (def rest-arities @{})
  (def arities @{:rest rest-arities})
-  (each clause clauses
+  (each clause data
   (print "CLAUSE:")
   (pp clause)
   (def patt (first clause))
@@ -314,7 +339,7 @@ Deferred until a later iteration of Ludus:
  (set (validator :ast) expr)
  (validate validator)
  (def name (ast :name))
- (def resolved (resolve-name ctx name))
+ (def resolved (ctx name))
  (when resolved
   (def {:line line :input input} (get-in ctx [name :token]))
   (array/push (validator :errors)
@@ -726,26 +751,33 @@ Deferred until a later iteration of Ludus:
 
 (set validate validate*)
 
+(defn- cleanup [validator]
+ (def declared (get-in validator [:status :declared] {}))
+ (when (any? declared)
+  (each declaration declared
+   (array/push (validator :errors) {:node declaration :msg "declared fn, but not defined"})))
+ validator)
+
 (defn valid [ast &opt ctx]
  (default ctx @{})
  (def validator (new-validator ast))
  (def base-ctx @{:^parent ctx})
  (set (validator :ctx) base-ctx)
- (validate validator))
+ (validate validator)
+ (cleanup validator))
 
 (import ./base :as b)
 
 (do
 # (comment
 (def source `
-fn foo {
- () -> foo (:foo)
-}
-
-foo ()
+fn foo
+fn bar () -> foo ()
+fn foo () -> bar ()
 `)
 (def scanned (s/scan source))
 (def parsed (p/parse scanned))
 (def validated (valid parsed))
+# (get-in validated [:status :declared])
 # (validated :ctx)
 )