diff --git a/examples/lang/fastcount.mcl b/examples/lang/fastcount.mcl
new file mode 100644
index 00000000..c365b35b
--- /dev/null
+++ b/examples/lang/fastcount.mcl
@@ -0,0 +1,32 @@
+import "fmt"
+import "test"
+
+# XXX: Because our function engine is not synchronous, absurdly-fast function
+# changing will result in these four files having vastly different values after
+# a certain amount of time. We probably want to fix this eventually.
+$count = test.fastcount()
+
+file "/tmp/mgmt-count0" {
+	content => fmt.printf("count is: %d\n", $count + 0),
+	state => $const.res.file.state.exists,
+}
+
+file "/tmp/mgmt-count1" {
+	content => fmt.printf("count is: %d\n", $count + 1),
+	state => $const.res.file.state.exists,
+}
+
+file "/tmp/mgmt-count2" {
+	content => fmt.printf("count is: %d\n", $count + 2),
+	state => $const.res.file.state.exists,
+}
+
+file "/tmp/mgmt-count" {
+	content => fmt.printf("count is: %d\n", $count),
+	state => $const.res.file.state.exists,
+}
+
+File["/tmp/mgmt-count0"] -> File["/tmp/mgmt-count1"]
+File["/tmp/mgmt-count0"] -> File["/tmp/mgmt-count2"]
+File["/tmp/mgmt-count1"] -> File["/tmp/mgmt-count"]
+File["/tmp/mgmt-count2"] -> File["/tmp/mgmt-count"]
diff --git a/lang/funcs/core/core.go b/lang/funcs/core/core.go
index b08db521..03680273 100644
--- a/lang/funcs/core/core.go
+++ b/lang/funcs/core/core.go
@@ -35,6 +35,7 @@ import (
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/regexp"
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/strings"
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/sys"
+	_ "github.com/purpleidea/mgmt/lang/funcs/core/test"
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/world"
 )
 
diff --git a/lang/funcs/core/test/fastcount_fact.go b/lang/funcs/core/test/fastcount_fact.go
new file mode 100644
index 00000000..59f43949
--- /dev/null
+++ b/lang/funcs/core/test/fastcount_fact.go
@@ -0,0 +1,83 @@
+// Mgmt
+// Copyright (C) 2013-2023+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package coretest
+
+import (
+	"context"
+
+	"github.com/purpleidea/mgmt/lang/funcs/facts"
+	"github.com/purpleidea/mgmt/lang/types"
+)
+
+const (
+	// FastCountFuncName is the name this fact is registered as. It's still a
+	// Func Name because this is the name space the fact is actually using.
+	FastCountFuncName = "fastcount"
+)
+
+func init() {
+	facts.ModuleRegister(ModuleName, FastCountFuncName, func() facts.Fact { return &FastCountFact{} }) // must register the fact and name
+}
+
+// FastCountFact is a fact that counts up as fast as possible from zero forever.
+type FastCountFact struct {
+	init *facts.Init
+}
+
+// String returns a simple name for this fact. This is needed so this struct can
+// satisfy the pgraph.Vertex interface.
+func (obj *FastCountFact) String() string {
+	return FastCountFuncName
+}
+
+// Validate makes sure we've built our struct properly. It is usually unused for
+// normal facts that users can use directly.
+//func (obj *FastCountFact) Validate() error {
+//	return nil
+//}
+
+// Info returns some static info about itself.
+func (obj *FastCountFact) Info() *facts.Info {
+	return &facts.Info{
+		Output: types.NewType("int"),
+	}
+}
+
+// Init runs some startup code for this fact.
+func (obj *FastCountFact) Init(init *facts.Init) error {
+	obj.init = init
+	return nil
+}
+
+// Stream returns the changing values that this fact has over time.
+func (obj *FastCountFact) Stream(ctx context.Context) error {
+	defer close(obj.init.Output) // always signal when we're done
+
+	count := int64(0)
+
+	// streams must generate an initial event on startup
+	for {
+		select {
+		case obj.init.Output <- &types.IntValue{V: count}:
+			count++
+
+		case <-ctx.Done():
+			return nil
+		}
+	}
+}
diff --git a/lang/funcs/core/test/test.go b/lang/funcs/core/test/test.go
new file mode 100644
index 00000000..0eee59f6
--- /dev/null
+++ b/lang/funcs/core/test/test.go
@@ -0,0 +1,23 @@
+// Mgmt
+// Copyright (C) 2013-2023+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package coretest
+
+const (
+	// ModuleName is the prefix given to all the functions in this module.
+	ModuleName = "test"
+)