diff --git a/lang/core/fmt/printf.go b/lang/core/fmt/printf.go
index 769023d1..8d92dde2 100644
--- a/lang/core/fmt/printf.go
+++ b/lang/core/fmt/printf.go
@@ -354,6 +354,16 @@ func (obj *PrintfFunc) Stream(ctx context.Context) error {
 	}
 }
 
+// Copy is implemented so that the obj.Type value is not lost if we copy this
+// function.
+func (obj *PrintfFunc) Copy() interfaces.Func {
+	return &PrintfFunc{
+		Type: obj.Type, // don't copy because we use this after unification
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
+
 // Call this function with the input args and return the value if it is possible
 // to do so at this time.
 func (obj *PrintfFunc) Call(ctx context.Context, args []types.Value) (types.Value, error) {
diff --git a/lang/core/golang/template.go b/lang/core/golang/template.go
index 41d69246..05c37ce6 100644
--- a/lang/core/golang/template.go
+++ b/lang/core/golang/template.go
@@ -393,6 +393,17 @@ func (obj *TemplateFunc) Stream(ctx context.Context) error {
 	}
 }
 
+// Copy is implemented so that the obj.built value is not lost if we copy this
+// function.
+func (obj *TemplateFunc) Copy() interfaces.Func {
+	return &TemplateFunc{
+		Type:  obj.Type, // don't copy because we use this after unification
+		built: obj.built,
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
+
 // Call this function with the input args and return the value if it is possible
 // to do so at this time.
 func (obj *TemplateFunc) Call(ctx context.Context, args []types.Value) (types.Value, error) {
diff --git a/lang/core/history.go b/lang/core/history.go
index e80fc2b0..28e51024 100644
--- a/lang/core/history.go
+++ b/lang/core/history.go
@@ -134,6 +134,16 @@ func (obj *HistoryFunc) Build(typ *types.Type) (*types.Type, error) {
 	return obj.sig(), nil
 }
 
+// Copy is implemented so that the type value is not lost if we copy this
+// function.
+func (obj *HistoryFunc) Copy() interfaces.Func {
+	return &HistoryFunc{
+		Type: obj.Type, // don't copy because we use this after unification
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
+
 // Validate makes sure we've built our struct properly. It is usually unused for
 // normal functions that users can use directly.
 func (obj *HistoryFunc) Validate() error {
diff --git a/lang/core/iter/filter.go b/lang/core/iter/filter.go
index 0f8743ed..fc771dad 100644
--- a/lang/core/iter/filter.go
+++ b/lang/core/iter/filter.go
@@ -459,3 +459,13 @@ func (obj *FilterFunc) replaceSubGraph(subgraphInput interfaces.Func) error {
 
 	return obj.init.Txn.Commit()
 }
+
+// Copy is implemented so that the type value is not lost if we copy this
+// function.
+func (obj *FilterFunc) Copy() interfaces.Func {
+	return &FilterFunc{
+		Type: obj.Type, // don't copy because we use this after unification
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
diff --git a/lang/core/iter/map.go b/lang/core/iter/map.go
index c2282fff..b03f39b0 100644
--- a/lang/core/iter/map.go
+++ b/lang/core/iter/map.go
@@ -454,3 +454,14 @@ func (obj *MapFunc) replaceSubGraph(subgraphInput interfaces.Func) error {
 
 	return obj.init.Txn.Commit()
 }
+
+// Copy is implemented so that the type values are not lost if we copy this
+// function.
+func (obj *MapFunc) Copy() interfaces.Func {
+	return &MapFunc{
+		Type:  obj.Type,  // don't copy because we use this after unification
+		RType: obj.RType, // don't copy because we use this after unification
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
diff --git a/lang/core/lookup.go b/lang/core/lookup.go
index a4947b8b..1fd24848 100644
--- a/lang/core/lookup.go
+++ b/lang/core/lookup.go
@@ -195,6 +195,20 @@ func (obj *LookupFunc) Build(typ *types.Type) (*types.Type, error) {
 	return obj.fn.Build(typ)
 }
 
+// Copy is implemented so that the type value is not lost if we copy this
+// function.
+func (obj *LookupFunc) Copy() interfaces.Func {
+	fn := &LookupFunc{
+		Type: obj.Type, // don't copy because we use this after unification
+
+		//init: obj.init, // likely gets overwritten anyways
+	}
+	if _, err := fn.Build(obj.Type); err != nil {
+		// ignore, since we just didn't set the type
+	}
+	return fn
+}
+
 // Validate tells us if the input struct takes a valid form.
 func (obj *LookupFunc) Validate() error {
 	if obj.fn == nil { // build must be run first
diff --git a/lang/core/lookup_default.go b/lang/core/lookup_default.go
index d40c9c1c..113c34d3 100644
--- a/lang/core/lookup_default.go
+++ b/lang/core/lookup_default.go
@@ -140,6 +140,21 @@ func (obj *LookupDefaultFunc) Build(typ *types.Type) (*types.Type, error) {
 	return obj.fn.Build(typ)
 }
 
+// Copy is implemented so that the type value is not lost if we copy this
+// function.
+func (obj *LookupDefaultFunc) Copy() interfaces.Func {
+	fn := &LookupDefaultFunc{
+		Type: obj.Type, // don't copy because we use this after unification
+		//fn: get this through Build()
+
+		//init: obj.init, // likely gets overwritten anyways
+	}
+	if _, err := fn.Build(obj.Type); err != nil {
+		// ignore, since we just didn't set the type
+	}
+	return fn
+}
+
 // Validate tells us if the input struct takes a valid form.
 func (obj *LookupDefaultFunc) Validate() error {
 	if obj.fn == nil { // build must be run first
diff --git a/lang/core/value/get.go b/lang/core/value/get.go
index 1671e4e4..18f17249 100644
--- a/lang/core/value/get.go
+++ b/lang/core/value/get.go
@@ -181,6 +181,16 @@ func (obj *GetFunc) Build(typ *types.Type) (*types.Type, error) {
 	return obj.sig(), nil
 }
 
+// Copy is implemented so that the type value is not lost if we copy this
+// function.
+func (obj *GetFunc) Copy() interfaces.Func {
+	return &GetFunc{
+		Type: obj.Type, // don't copy because we use this after unification
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
+
 // Validate makes sure we've built our struct properly. It is usually unused for
 // normal functions that users can use directly.
 func (obj *GetFunc) Validate() error {
diff --git a/lang/core/world/schedule.go b/lang/core/world/schedule.go
index 56ec46ee..94961a40 100644
--- a/lang/core/world/schedule.go
+++ b/lang/core/world/schedule.go
@@ -247,6 +247,17 @@ func (obj *ScheduleFunc) Build(typ *types.Type) (*types.Type, error) {
 	return obj.sig(), nil
 }
 
+// Copy is implemented so that the type value is not lost if we copy this
+// function.
+func (obj *ScheduleFunc) Copy() interfaces.Func {
+	return &ScheduleFunc{
+		Type:  obj.Type, // don't copy because we use this after unification
+		built: obj.built,
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
+
 // Validate tells us if the input struct takes a valid form.
 func (obj *ScheduleFunc) Validate() error {
 	if !obj.built {
diff --git a/lang/funcs/operators/operators.go b/lang/funcs/operators/operators.go
index c8b6fb07..b0731421 100644
--- a/lang/funcs/operators/operators.go
+++ b/lang/funcs/operators/operators.go
@@ -722,6 +722,16 @@ func (obj *OperatorFunc) Stream(ctx context.Context) error {
 	}
 }
 
+// Copy is implemented so that the obj.Type value is not lost if we copy this
+// function.
+func (obj *OperatorFunc) Copy() interfaces.Func {
+	return &OperatorFunc{
+		Type: obj.Type, // don't copy because we use this after unification
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
+
 // Call this function with the input args and return the value if it is possible
 // to do so at this time.
 func (obj *OperatorFunc) Call(ctx context.Context, args []types.Value) (types.Value, error) {