thread.run.recurrent is now the main function.

libs/thread.liq

@@ -1,19 +1,13 @@
-# TODO: we cannot easly define recursive functions with optional arguments for
-# now, see #1018.
-def rec thread.run.recurrent(~fast, ~delay, f)
-  def f ()
-    delay = f ()
-    if delay >= 0. then thread.run.recurrent(fast=fast, delay=delay, f) end
-  end
-  thread.run(fast=fast, delay=delay, f)
-end
-
-# Run a recurrent function in a separate thread.
+# Run a function in a separate thread.
 # @category Control
 # @param ~fast Whether the thread is supposed to return quickly or not. Typically, blocking tasks (e.g. fetching data over the internet) should not be considered to be fast. When set to `false` its priority will be lowered below that of request resolutions and fast timeouts. This is only effective if you set a dedicated queue for fast tasks, see the "scheduler" settings for more details.
 # @param ~delay Delay (in sec.) after which the thread should be lauched.
 # @param f Function to execute.
-def thread.run.recurrent(~fast=true, ~delay=0., f)
+def thread.run(~fast=true, ~delay=0., f)
+  def f() =
+    f()
+    (-1.)
+  end
   thread.run.recurrent(fast=fast, delay=delay, f)
 end
 

src/lang/builtins_thread.ml

@@ -23,7 +23,7 @@
 open Lang_builtins
 
 let () =
-  add_builtin "thread.run" ~cat:Control
+  add_builtin "thread.run.recurrent" ~cat:Control
     [
       "fast", Lang.bool_t, Some (Lang.bool true),
       Some "Whether the thread is supposed to return quickly or not. Typically, \
@@ -34,10 +34,13 @@ let () =
             \"scheduler\" settings for more details." ;
       "delay", Lang.float_t, Some (Lang.float 0.),
       Some "Delay (in sec.) after which the thread should be lauched.";
-      "", Lang.fun_t [] Lang.unit_t, None, Some "Function to execute."
+      "", Lang.fun_t [] Lang.float_t, None,
+      Some "Function to execute recurrently. The returned value is the delay (in \
+            sec.) in which the function should be run again (it won't be run if \
+            the value is strictly negative)."
     ]
     Lang.unit_t
-    ~descr:"Run a function in a separate thread."
+    ~descr:"Run a recurrent function in a separate thread."
     (fun p ->
        let delay = Lang.to_float (List.assoc "delay" p) in
        let f = List.assoc "" p in
@@ -47,14 +50,16 @@ let () =
          else
            Tutils.Blocking
        in
-       let task =
+       let rec task delay =
          { Duppy.Task.
            priority = priority ;
            events   = [`Delay delay] ;
-           handler  = fun _ -> Lang.to_unit (Lang.apply ~t:Lang.unit_t f []); []
+           handler  = fun _ ->
+             let d = Lang.to_float (Lang.apply ~t:Lang.float_t f []) in
+             if d >= 0. then [task delay] else []
          }
        in
-       Duppy.Task.add Tutils.scheduler task;
+       Duppy.Task.add Tutils.scheduler (task delay);
        Lang.unit)
 
 let () =