lang: Improve graph shape with speculative execution

Most of the time, we don't need to have a dynamic call sub graph, since
the actual function call could be represented statically as it
originally was before lambda functions were implemented. Simplifying the
graph shape has important performance benefits in terms of both keep the
graph smaller (memory, etc) and in avoiding the need to run transactions
at runtime (speed) to reshape the graph.

Co-authored-by: Samuel Gélineau <gelisam@gmail.com>

lang/core/world/collect/res.go

@@ -118,6 +118,8 @@ func (obj *ResFunc) Info() *interfaces.Info {
 	return &interfaces.Info{
 		Pure: false,
 		Memo: false,
+		Fast: false,
+		Spec: false,
 		Sig:  obj.sig(),
 		Err:  obj.Validate(),
 	}
@@ -225,6 +227,9 @@ func (obj *ResFunc) Stream(ctx context.Context) error {
 // to do so at this time. This was previously getValue which gets the value
 // we're looking for.
 func (obj *ResFunc) Call(ctx context.Context, args []types.Value) (types.Value, error) {
+	if len(args) < 1 {
+		return nil, fmt.Errorf("not enough args")
+	}
 	kind := args[0].Str()
 	if kind == "" {
 		return nil, fmt.Errorf("resource kind is empty")
@@ -241,6 +246,9 @@ func (obj *ResFunc) Call(ctx context.Context, args []types.Value) (types.Value,
 	}
 	filters = append(filters, filter)
 
+	if obj.init == nil {
+		return nil, funcs.ErrCantSpeculate
+	}
 	resOutput, err := obj.init.World.ResCollect(ctx, filters)
 	if err != nil {
 		return nil, err