diff --git a/mers/Cargo.toml b/mers/Cargo.toml
index de973e7..abc024e 100644
--- a/mers/Cargo.toml
+++ b/mers/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mers"
-version = "0.9.26"
+version = "0.9.28"
 edition = "2021"
 license = "MIT OR Apache-2.0"
 description = "dynamically typed but type-checked programming language"
@@ -15,7 +15,7 @@ default = ["colored-output"]
 colored-output = ["mers_lib/ecolor-term", "mers_lib/pretty-print", "dep:colored"]
 
 [dependencies]
-mers_lib = "0.9.26"
+mers_lib = "0.9.28"
 # mers_lib = { path = "../mers_lib" }
 clap = { version = "4.3.19", features = ["derive"] }
 colored = { version = "2.1.0", optional = true }
diff --git a/mers_lib/Cargo.toml b/mers_lib/Cargo.toml
index bbb929d..3a8cc96 100755
--- a/mers_lib/Cargo.toml
+++ b/mers_lib/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mers_lib"
-version = "0.9.26"
+version = "0.9.28"
 edition = "2021"
 license = "MIT OR Apache-2.0"
 description = "library to use the mers language in other projects"
diff --git a/mers_lib/src/data/defs.rs b/mers_lib/src/data/defs.rs
index ebbe160..b86f3ff 100755
--- a/mers_lib/src/data/defs.rs
+++ b/mers_lib/src/data/defs.rs
@@ -6,33 +6,70 @@ pub fn assign(from: &Data, target: &Data) {
         .as_any()
         .downcast_ref::<crate::data::reference::Reference>()
     {
-        *r.0.write().unwrap() = from.clone();
-    } else if let (Some(from), Some(target)) = (
+        *r.write() = from.clone();
+    } else if let (Some((from, from_ref)), Some(target)) = (
         from.get()
             .as_any()
-            .downcast_ref::<crate::data::tuple::Tuple>(),
+            .downcast_ref::<crate::data::tuple::Tuple>()
+            .map(|v| (v.clone(), false))
+            .or_else(|| {
+                from.get()
+                    .as_any()
+                    .downcast_ref::<crate::data::reference::Reference>()
+                    .and_then(|r| {
+                        r.read()
+                            .get()
+                            .as_any()
+                            .downcast_ref::<crate::data::tuple::Tuple>()
+                            .map(|v| (v.clone_refs(), true))
+                    })
+            }),
         target
             .get()
             .as_any()
             .downcast_ref::<crate::data::tuple::Tuple>(),
     ) {
-        for (from, target) in from.0.iter().zip(target.0.iter()) {
-            assign(from, target);
+        for (from, target) in from.0.into_iter().zip(target.0.iter()) {
+            if from_ref {
+                assign(&Data::new(from), &*target.read());
+            } else {
+                assign(&*from.read(), &*target.read());
+            }
         }
-    } else if let (Some(from), Some(target)) = (
+    } else if let (Some((from, from_ref)), Some(target)) = (
         from.get()
             .as_any()
-            .downcast_ref::<crate::data::object::Object>(),
+            .downcast_ref::<crate::data::object::Object>()
+            .map(|v| (v.clone(), false))
+            .or_else(|| {
+                from.get()
+                    .as_any()
+                    .downcast_ref::<crate::data::reference::Reference>()
+                    .and_then(|r| {
+                        r.read()
+                            .get()
+                            .as_any()
+                            .downcast_ref::<crate::data::object::Object>()
+                            .map(|v| (v.clone_refs(), true))
+                    })
+            }),
         target
             .get()
             .as_any()
             .downcast_ref::<crate::data::object::Object>(),
     ) {
         for (field, target) in target.iter() {
-            let from = from
-                .get(*field)
-                .expect("type-checks should guarantee that from has every field of target");
-            assign(from, target);
+            if from_ref {
+                let from = from
+                    .get_mut(*field)
+                    .expect("type-checks should guarantee that from has every field of target");
+                assign(&Data::new(from.clone_ref()), &*target.read());
+            } else {
+                let from = from
+                    .get(*field)
+                    .expect("type-checks should guarantee that from has every field of target");
+                assign(&from, &*target.read());
+            }
         }
     } else {
         unreachable!("invalid assignment")
diff --git a/mers_lib/src/data/mod.rs b/mers_lib/src/data/mod.rs
index 724babe..bb3b906 100755
--- a/mers_lib/src/data/mod.rs
+++ b/mers_lib/src/data/mod.rs
@@ -225,7 +225,7 @@ impl Data {
         Self::new(tuple::Tuple(vec![]))
     }
     pub fn one_tuple(v: Self) -> Self {
-        Self::new(tuple::Tuple(vec![v]))
+        Self::new(tuple::Tuple::from([v]))
     }
     /// Returns true if self is `()`.
     pub fn is_zero_tuple(&self) -> bool {
@@ -253,13 +253,13 @@ impl Data {
             None
         }
     }
-    pub fn get(&self) -> RwLockReadGuard<Box<dyn MersData>> {
+    pub fn get(&'_ self) -> RwLockReadGuard<'_, Box<dyn MersData>> {
         self.data.read().unwrap()
     }
-    pub fn get_mut_unchecked(&self) -> RwLockWriteGuard<Box<dyn MersData>> {
+    pub fn get_mut_unchecked(&'_ self) -> RwLockWriteGuard<'_, Box<dyn MersData>> {
         self.data.write().unwrap()
     }
-    pub fn try_get_mut(&self) -> Option<RwLockWriteGuard<Box<dyn MersData>>> {
+    pub fn try_get_mut(&'_ self) -> Option<RwLockWriteGuard<'_, Box<dyn MersData>>> {
         if self.is_mut && self.counts.0.load(std::sync::atomic::Ordering::Relaxed) == 0 {
             Some(self.get_mut_unchecked())
         } else {
@@ -268,7 +268,7 @@ impl Data {
     }
     /// like try_get_mut, but instead of returning `None` this function `get()`s the data and clones it.
     /// When cloning data, this transforms `self` into a `Data` with `is_mut: true`, hence the `&mut self` parameter.
-    pub fn get_mut(&mut self) -> RwLockWriteGuard<Box<dyn MersData>> {
+    pub fn get_mut(&'_ mut self) -> RwLockWriteGuard<'_, Box<dyn MersData>> {
         if self.try_get_mut().is_none() {
             #[cfg(debug_assertions)]
             eprintln!(
diff --git a/mers_lib/src/data/object.rs b/mers_lib/src/data/object.rs
index c387b55..3f3399f 100644
--- a/mers_lib/src/data/object.rs
+++ b/mers_lib/src/data/object.rs
@@ -7,18 +7,33 @@ use crate::info::DisplayInfo;
 
 use super::{Data, MersData, MersDataWInfo, MersType, Type};
 
-#[derive(Debug, PartialEq, Clone)]
-pub struct Object(Vec<(usize, Data)>);
+#[derive(Debug, PartialEq)]
+pub struct Object(Vec<(usize, super::reference::Reference)>);
 impl Object {
-    pub fn new(v: Vec<(usize, Data)>) -> Self {
-        Self(v)
+    pub fn new(v: impl IntoIterator<Item = (usize, Data)>) -> Self {
+        Self(
+            v.into_iter()
+                .map(|(i, d)| (i, super::reference::Reference::from(d)))
+                .collect(),
+        )
     }
-    pub fn get(&self, f: usize) -> Option<&Data> {
-        self.iter().find(|v| v.0 == f).map(|v| &v.1)
+    pub fn get(&self, f: usize) -> Option<Data> {
+        self.iter().find(|v| v.0 == f).map(|v| v.1.read().clone())
     }
-    pub fn iter(&self) -> std::slice::Iter<(usize, Data)> {
+    pub fn get_mut(&self, f: usize) -> Option<&super::reference::Reference> {
+        self.iter().find(|v| v.0 == f).map(|(_, v)| v)
+    }
+    pub fn iter(&'_ self) -> std::slice::Iter<'_, (usize, super::reference::Reference)> {
         self.0.iter()
     }
+    pub fn clone_refs(&self) -> Self {
+        Self(self.0.iter().map(|(i, r)| (*i, r.clone_ref())).collect())
+    }
+}
+impl Clone for Object {
+    fn clone(&self) -> Self {
+        Self(self.0.iter().map(|(i, r)| (*i, r.clone_data())).collect())
+    }
 }
 #[derive(Debug, Clone)]
 pub struct ObjectT(Vec<(usize, Type)>);
@@ -29,7 +44,7 @@ impl ObjectT {
     pub fn get(&self, f: usize) -> Option<&Type> {
         self.iter().find(|v| v.0 == f).map(|v| &v.1)
     }
-    pub fn iter(&self) -> std::slice::Iter<(usize, Type)> {
+    pub fn iter(&'_ self) -> std::slice::Iter<'_, (usize, Type)> {
         self.0.iter()
     }
     fn len(&self) -> usize {
@@ -49,7 +64,7 @@ impl MersData for Object {
                 f,
                 "{}: {}",
                 info.get_object_field_name(*field),
-                val.get().with_display(info)
+                val.read().get().with_display(info)
             )?;
             comma_sep = true;
         }
@@ -69,7 +84,7 @@ impl MersData for Object {
     fn as_type(&self) -> Type {
         Type::new(ObjectT(
             self.iter()
-                .map(|(n, v)| (n.clone(), v.get().as_type()))
+                .map(|(n, v)| (n.clone(), v.read().get().as_type()))
                 .collect(),
         ))
     }
diff --git a/mers_lib/src/data/reference.rs b/mers_lib/src/data/reference.rs
index 1cd6303..c6f00a4 100755
--- a/mers_lib/src/data/reference.rs
+++ b/mers_lib/src/data/reference.rs
@@ -1,14 +1,32 @@
 use std::{
     any::Any,
-    sync::{Arc, RwLock},
+    sync::{Arc, RwLock, RwLockReadGuard, RwLockWriteGuard},
 };
 
 use crate::{errors::CheckError, info::DisplayInfo};
 
 use super::{Data, MersData, MersType, Type};
 
-#[derive(Debug, Clone)]
-pub struct Reference(pub Arc<RwLock<Data>>);
+#[derive(Debug)]
+pub struct Reference(Arc<RwLock<Data>>);
+
+impl Reference {
+    /// Creates a reference from data,
+    /// so that the original data can't be
+    /// modified through the new reference.
+    pub fn from(data: Data) -> Self {
+        Self(Arc::new(RwLock::new(data.mkref().0)))
+    }
+    pub fn raw(reference: Arc<RwLock<Data>>) -> Self {
+        Self(reference)
+    }
+    pub fn read(&'_ self) -> RwLockReadGuard<'_, Data> {
+        self.0.read().unwrap()
+    }
+    pub fn write(&'_ self) -> RwLockWriteGuard<'_, Data> {
+        self.0.write().unwrap()
+    }
+}
 
 impl MersData for Reference {
     fn display(&self, info: &DisplayInfo<'_>, f: &mut std::fmt::Formatter) -> std::fmt::Result {
@@ -79,7 +97,7 @@ impl MersData for Reference {
         }
     }
     fn clone(&self) -> Box<dyn MersData> {
-        Box::new(Clone::clone(self))
+        Box::new(self.clone_ref())
     }
     fn as_type(&self) -> Type {
         Type::new(ReferenceT(self.0.read().unwrap().get().as_type()))
@@ -95,6 +113,23 @@ impl MersData for Reference {
     }
 }
 
+impl Reference {
+    pub fn clone_ref(&self) -> Self {
+        Self(Arc::clone(&self.0))
+    }
+    pub fn clone_data(&self) -> Self {
+        Self(Arc::new(RwLock::new(
+            self.0.read().unwrap().clone().mkref().0,
+        )))
+    }
+}
+
+impl PartialEq for Reference {
+    fn eq(&self, other: &Self) -> bool {
+        *self.0.read().unwrap() == *other.0.read().unwrap()
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct ReferenceT(pub Type);
 impl MersType for ReferenceT {
diff --git a/mers_lib/src/data/tuple.rs b/mers_lib/src/data/tuple.rs
index e4ab58b..55faba1 100755
--- a/mers_lib/src/data/tuple.rs
+++ b/mers_lib/src/data/tuple.rs
@@ -4,15 +4,38 @@ use crate::{errors::CheckError, info::DisplayInfo};
 
 use super::{Data, MersData, MersType, Type};
 
-#[derive(Debug, Clone)]
-pub struct Tuple(pub Vec<Data>);
+#[derive(Debug)]
+pub struct Tuple(pub Vec<super::reference::Reference>);
 
 impl Tuple {
+    pub fn empty() -> Self {
+        Self(vec![])
+    }
+    pub fn from(elems: impl IntoIterator<Item = Data>) -> Self {
+        Self(
+            elems
+                .into_iter()
+                .map(|d| super::reference::Reference::from(d))
+                .collect(),
+        )
+    }
     pub fn len(&self) -> usize {
         self.0.len()
     }
-    pub fn get(&self, i: usize) -> Option<&Data> {
-        self.0.get(i)
+    pub fn get(&self, i: usize) -> Option<Data> {
+        self.0.get(i).map(|v| v.read().clone())
+    }
+    pub fn get_mut(&self, i: usize) -> Option<super::reference::Reference> {
+        self.0.get(i).map(|v| v.clone_ref())
+    }
+    pub fn clone_refs(&self) -> Self {
+        Self(self.0.iter().map(|r| r.clone_ref()).collect())
+    }
+}
+
+impl Clone for Tuple {
+    fn clone(&self) -> Self {
+        Self(self.0.iter().map(|r| r.clone_data()).collect())
     }
 }
 
@@ -23,7 +46,7 @@ impl MersData for Tuple {
             if i > 0 {
                 write!(f, ", ")?;
             }
-            c.get().display(info, f)?;
+            c.read().get().display(info, f)?;
         }
         write!(f, ")")?;
         Ok(())
@@ -39,13 +62,21 @@ impl MersData for Tuple {
         &self,
         _gi: &crate::program::run::RunLocalGlobalInfo,
     ) -> Option<Box<dyn Iterator<Item = Result<Data, CheckError>>>> {
-        Some(Box::new(self.0.clone().into_iter().map(Ok)))
+        Some(Box::new(
+            Clone::clone(self)
+                .0
+                .into_iter()
+                .map(|r| r.read().clone())
+                .map(Ok),
+        ))
     }
     fn clone(&self) -> Box<dyn MersData> {
         Box::new(Clone::clone(self))
     }
     fn as_type(&self) -> Type {
-        Type::new(TupleT(self.0.iter().map(|v| v.get().as_type()).collect()))
+        Type::new(TupleT(
+            self.0.iter().map(|v| v.read().get().as_type()).collect(),
+        ))
     }
     fn as_any(&self) -> &dyn Any {
         self
diff --git a/mers_lib/src/errors/mod.rs b/mers_lib/src/errors/mod.rs
index affd25a..0fc507b 100644
--- a/mers_lib/src/errors/mod.rs
+++ b/mers_lib/src/errors/mod.rs
@@ -178,7 +178,7 @@ impl CheckErrorHRConfig {
             .color(s, EColor::Indent(self.color_index), &mut t);
         return t;
     }
-    pub fn indent_start(&self, right: bool) -> IndentStr {
+    pub fn indent_start(&'_ self, right: bool) -> IndentStr<'_> {
         IndentStr(
             &self.idt_start,
             self.color(
@@ -186,13 +186,13 @@ impl CheckErrorHRConfig {
             ),
         )
     }
-    pub fn indent_default(&self, right: bool) -> IndentStr {
+    pub fn indent_default(&'_ self, right: bool) -> IndentStr<'_> {
         IndentStr(
             &self.idt_default,
             self.color(Self::CHARS[self.style as usize][1][right as usize]),
         )
     }
-    pub fn indent_end(&self, right: bool) -> IndentStr {
+    pub fn indent_end(&'_ self, right: bool) -> IndentStr<'_> {
         IndentStr(
             &self.idt_end,
             self.color(
@@ -200,7 +200,7 @@ impl CheckErrorHRConfig {
             ),
         )
     }
-    pub fn indent_single(&self, right: bool) -> IndentStr {
+    pub fn indent_single(&'_ self, right: bool) -> IndentStr<'_> {
         IndentStr(
             &self.idt_single,
             self.color(if self.is_inner {
diff --git a/mers_lib/src/program/configs/gen/mod.rs b/mers_lib/src/program/configs/gen/mod.rs
index 8963176..0be93af 100644
--- a/mers_lib/src/program/configs/gen/mod.rs
+++ b/mers_lib/src/program/configs/gen/mod.rs
@@ -43,7 +43,7 @@ impl<A: FromMersData> FromMersData for OneOrNone<A> {
             if v.0.is_empty() {
                 f(Some(Self(None)))
             } else {
-                A::try_represent(v.0[0].get().as_ref(), |v1| {
+                A::try_represent(v.0[0].read().get().as_ref(), |v1| {
                     if let Some(va) = v1 {
                         f(Some(Self(Some(va))))
                     } else {
@@ -205,7 +205,7 @@ impl<A: FromMersData> FromMersData for (A,) {
             .downcast_ref::<data::tuple::Tuple>()
             .filter(|v| v.0.len() == 1)
         {
-            A::try_represent(v.0[0].get().as_ref(), |v1| {
+            A::try_represent(v.0[0].read().get().as_ref(), |v1| {
                 if let Some(va) = v1 {
                     f(Some((va,)))
                 } else {
@@ -222,7 +222,7 @@ impl<A: ToMersData> ToMersData for (A,) {
         Type::new(data::tuple::TupleT(vec![A::as_type_to()]))
     }
     fn represent(self) -> Data {
-        Data::new(data::tuple::Tuple(vec![self.0.represent()]))
+        Data::new(data::tuple::Tuple::from([self.0.represent()]))
     }
 }
 
@@ -242,9 +242,9 @@ impl<A: FromMersData, B: FromMersData> FromMersData for (A, B) {
             .downcast_ref::<data::tuple::Tuple>()
             .filter(|v| v.0.len() == 2)
         {
-            A::try_represent(v.0[0].get().as_ref(), |v1| {
+            A::try_represent(v.0[0].read().get().as_ref(), |v1| {
                 if let Some(va) = v1 {
-                    B::try_represent(v.0[1].get().as_ref(), |v2| {
+                    B::try_represent(v.0[1].read().get().as_ref(), |v2| {
                         if let Some(vb) = v2 {
                             f(Some((va, vb)))
                         } else {
@@ -265,7 +265,7 @@ impl<A: ToMersData, B: ToMersData> ToMersData for (A, B) {
         Type::new(data::tuple::TupleT(vec![A::as_type_to(), B::as_type_to()]))
     }
     fn represent(self) -> Data {
-        Data::new(data::tuple::Tuple(vec![
+        Data::new(data::tuple::Tuple::from([
             self.0.represent(),
             self.1.represent(),
         ]))
@@ -288,11 +288,11 @@ impl<A: FromMersData, B: FromMersData, C: FromMersData> FromMersData for (A, B,
             .downcast_ref::<data::tuple::Tuple>()
             .filter(|v| v.0.len() == 3)
         {
-            A::try_represent(v.0[0].get().as_ref(), |v1| {
+            A::try_represent(v.0[0].read().get().as_ref(), |v1| {
                 if let Some(va) = v1 {
-                    B::try_represent(v.0[1].get().as_ref(), |v2| {
+                    B::try_represent(v.0[1].read().get().as_ref(), |v2| {
                         if let Some(vb) = v2 {
-                            C::try_represent(v.0[2].get().as_ref(), |v3| {
+                            C::try_represent(v.0[2].read().get().as_ref(), |v3| {
                                 if let Some(vc) = v3 {
                                     f(Some((va, vb, vc)))
                                 } else {
@@ -321,7 +321,7 @@ impl<A: ToMersData, B: ToMersData, C: ToMersData> ToMersData for (A, B, C) {
         ]))
     }
     fn represent(self) -> Data {
-        Data::new(data::tuple::Tuple(vec![
+        Data::new(data::tuple::Tuple::from([
             self.0.represent(),
             self.1.represent(),
             self.2.represent(),
diff --git a/mers_lib/src/program/configs/util.rs b/mers_lib/src/program/configs/util.rs
index 438d949..b07d71b 100644
--- a/mers_lib/src/program/configs/util.rs
+++ b/mers_lib/src/program/configs/util.rs
@@ -100,8 +100,10 @@ pub fn to_mers_func_concrete_string_string_to_any(
         move |a, _| {
             let a = a.get();
             let a = &a.as_any().downcast_ref::<data::tuple::Tuple>().unwrap().0;
-            let l = a[0].get();
-            let r = a[1].get();
+            let l = a[0].read();
+            let l = l.get();
+            let r = a[1].read();
+            let r = r.get();
             f(
                 l.as_any()
                     .downcast_ref::<data::string::String>()
diff --git a/mers_lib/src/program/configs/with_base.rs b/mers_lib/src/program/configs/with_base.rs
index 5325bcd..61c94b6 100755
--- a/mers_lib/src/program/configs/with_base.rs
+++ b/mers_lib/src/program/configs/with_base.rs
@@ -1,5 +1,5 @@
 use std::{
-    sync::{Arc, Mutex, RwLock},
+    sync::{Arc, Mutex},
     time::{Duration, Instant},
 };
 
@@ -68,10 +68,12 @@ impl Config {
                 run: Arc::new(|a, i| {
                     let a = a.get();
                     let a = a.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                    let arg_ref = a.0[0].get();
+                    let arg_ref = a.0[0].read();
+                    let arg_ref = arg_ref.get();
                     let arg_ref = arg_ref.as_any().downcast_ref::<data::reference::Reference>().unwrap();
-                    let mut arg = arg_ref.0.write().unwrap();
-                    let func = a.0[1].get();
+                    let mut arg = arg_ref.write();
+                    let func = a.0[1].read();
+                    let func = func.get();
                     *arg = func.execute(arg.clone(), &i.global).unwrap()?;
                     Ok(Data::empty_tuple())
                 }),
@@ -168,7 +170,7 @@ impl Config {
                 fixed_type_out: Arc::new(Mutex::new(None)),
                 out: Ok(Arc::new(|a, _i| Ok(Type::new(data::reference::ReferenceT(a.clone()))))),
                 run: Arc::new(|a, _i| {
-                    Ok(Data::new(data::reference::Reference(Arc::new(RwLock::new(a.clone())))))
+                    Ok(Data::new(data::reference::Reference::from(a)))
                 }),
                 inner_statements: None,
             },
@@ -188,7 +190,7 @@ impl Config {
                         .as_any()
                         .downcast_ref::<data::reference::Reference>()
                     {
-                        Ok(r.0.write().unwrap().clone())
+                        Ok(r.read().clone())
                     } else {
                         Err("called deref on non-reference".into())
                     }
diff --git a/mers_lib/src/program/configs/with_command_running.rs b/mers_lib/src/program/configs/with_command_running.rs
index 6c8e98a..1bf9a1f 100755
--- a/mers_lib/src/program/configs/with_command_running.rs
+++ b/mers_lib/src/program/configs/with_command_running.rs
@@ -53,7 +53,7 @@ impl Config {
                 run: Arc::new(|a, i| {
                     let a = a.get();
                     let cmd = a.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                    let (cmd, args) = (&cmd.0[0], &cmd.0[1]);
+                    let (cmd, args) = (&cmd.0[0].read(), &cmd.0[1].read());
                     let cmd = cmd.get();
                     let (cmd, args) = (
                         cmd.as_any().downcast_ref::<data::string::String>().unwrap(),
@@ -74,7 +74,7 @@ impl Config {
                                 String::from_utf8_lossy(&output.stdout).into_owned();
                             let stderr =
                                 String::from_utf8_lossy(&output.stderr).into_owned();
-                            Ok(Data::new(data::tuple::Tuple(vec![
+                            Ok(Data::new(data::tuple::Tuple::from([
                                 status,
                                 Data::new(data::string::String(stdout)),
                                 Data::new(data::string::String(stderr)),
@@ -106,7 +106,7 @@ impl Config {
                 run: Arc::new(|a, i| {
                     let a = a.get();
                     let cmd = a.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                    let (cmd, args) = (&cmd.0[0], &cmd.0[1]);
+                    let (cmd, args) = (&cmd.0[0].read(), &cmd.0[1].read());
                     let cmd = cmd.get();
                     let (cmd, args) = (
                         cmd.as_any().downcast_ref::<data::string::String>().unwrap(),
@@ -215,8 +215,10 @@ impl Config {
                 run: Arc::new(|a, i| {
                     let a = a.get();
                     let tuple = a.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                    let child = tuple.0[0].get();
-                    let bytes = tuple.0[1].get();
+                    let child = tuple.0[0].read();
+                    let child = child.get();
+                    let bytes = tuple.0[1].read();
+                    let bytes = bytes.get();
                     let child = child.as_any().downcast_ref::<ChildProcess>().unwrap();
                     let mut child = child.0.lock().unwrap();
                     let buf = bytes.iterable(&i.global).unwrap().map(|v| v.map(|v| v.get().as_any().downcast_ref::<data::byte::Byte>().unwrap().0)).collect::<Result<Vec<_>, _>>()?;
@@ -246,8 +248,10 @@ impl Config {
                 run: Arc::new(|a, _i| {
                     let a = a.get();
                     let tuple = a.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                    let child = tuple.0[0].get();
-                    let string = tuple.0[1].get();
+                    let child = tuple.0[0].read();
+                    let child = child.get();
+                    let string = tuple.0[1].read();
+                    let string = string.get();
                     let child = child.as_any().downcast_ref::<ChildProcess>().unwrap();
                     let mut child = child.0.lock().unwrap();
                     let buf = string.as_any().downcast_ref::<data::string::String>().unwrap().0.as_bytes();
diff --git a/mers_lib/src/program/configs/with_fs.rs b/mers_lib/src/program/configs/with_fs.rs
index 14443d0..e0ff7c4 100644
--- a/mers_lib/src/program/configs/with_fs.rs
+++ b/mers_lib/src/program/configs/with_fs.rs
@@ -76,7 +76,8 @@ impl Config {
                         .as_any()
                         .downcast_ref::<Tuple>()
                         .expect("got non-tuple argument to fs_read_text");
-                    let (a, b) = (a.0[0].get(), a.0[1].get());
+                    let (a, b) = (a.0[0].read(), a.0[1].read());
+                    let (a, b) = (a.get(), b.get());
                     let a = a
                         .as_any()
                         .downcast_ref::<data::string::String>()
diff --git a/mers_lib/src/program/configs/with_iters.rs b/mers_lib/src/program/configs/with_iters.rs
index 7b256fa..c83079b 100755
--- a/mers_lib/src/program/configs/with_iters.rs
+++ b/mers_lib/src/program/configs/with_iters.rs
@@ -74,7 +74,8 @@ impl Config {
                 }, |a, _| {
                     let a = a.get();
                     let a = a.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                    let (v, e) = (a.0[0].get(), a.0[1].get());
+                    let (v, e) = (a.0[0].read(), a.0[1].read());
+                    let (v, e) = (v.get(), e.get());
                     let (v, e) = (v.as_any().downcast_ref::<data::int::Int>().unwrap(), e.as_any().downcast_ref::<data::int::Int>().unwrap());
                     Ok(Data::new(Range(v.0, e.0)))
                 }
@@ -114,7 +115,8 @@ impl Config {
                 }, |a, _| {
                     let a = a.get();
                     let a = a.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                    let (v, e) = (a.0[0].get(), a.0[1].get());
+                    let (v, e) = (a.0[0].read(), a.0[1].read());
+                    let (v, e) = (v.get(), e.get());
                     let (v, e) = (v.as_any().downcast_ref::<data::int::Int>().unwrap(), e.as_any().downcast_ref::<data::int::Int>().unwrap());
                     if let Some(e) = e.0.checked_sub(1) {
                         Ok(Data::new(Range(v.0, e)))
@@ -495,7 +497,7 @@ impl MersData for Iter {
                         .iterable(&gi)?
                         .enumerate()
                         .map(|(i, v)| match v {
-                            Ok(v) => Ok(Data::new(data::tuple::Tuple(vec![
+                            Ok(v) => Ok(Data::new(data::tuple::Tuple::from([
                                 Data::new(data::int::Int(i as _)),
                                 v,
                             ]))),
diff --git a/mers_lib/src/program/configs/with_list.rs b/mers_lib/src/program/configs/with_list.rs
index 9638536..5b28ad4 100755
--- a/mers_lib/src/program/configs/with_list.rs
+++ b/mers_lib/src/program/configs/with_list.rs
@@ -65,9 +65,7 @@ impl Config {
                             .as_any()
                             .downcast_ref::<data::reference::Reference>()
                             .unwrap()
-                            .0
                             .write()
-                            .unwrap()
                             .get_mut()
                             .mut_any()
                             .downcast_mut::<List>()
@@ -128,20 +126,18 @@ impl Config {
                     run: Arc::new(|a, _i| {
                         let tuple = a.get();
                         let tuple = tuple.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                        tuple.0[0]
+                        tuple.0[0].read()
                             .get()
                             .as_any()
                             .downcast_ref::<data::reference::Reference>()
                             .unwrap()
-                            .0
                             .write()
-                            .unwrap()
                             .get_mut()
                             .mut_any()
                             .downcast_mut::<List>()
                             .unwrap()
                             .0
-                            .push(tuple.0[1].clone());
+                            .push(tuple.0[1].read().clone());
                             Ok(Data::empty_tuple())
                     }),
                 inner_statements: None,
@@ -197,15 +193,14 @@ impl Config {
                     run: Arc::new(|a, _i| {
                         let tuple = a.get();
                         let tuple = tuple.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                        let index = tuple.0[1].get().as_any().downcast_ref::<data::int::Int>().unwrap().0 as usize;
-                            let list = tuple.0[0]
-                            .get();
+                        let index = tuple.0[1].read().get().as_any().downcast_ref::<data::int::Int>().unwrap().0 as usize;
+                            let list = tuple.0[0].read();
+                            let list = list.get();
                             let mut list = list
                             .as_any()
                             .downcast_ref::<data::reference::Reference>()
                             .unwrap()
-                            .0
-                            .write().unwrap();
+                            .write();
                             let mut list = list
                             .get_mut();
                             let list = list
@@ -215,7 +210,7 @@ impl Config {
                         if index > list.0.len() {
                             Ok(Data::new(data::bool::Bool(false)))
                         } else {
-                            list.0.insert(index, tuple.0[2].clone());
+                            list.0.insert(index, tuple.0[2].read().clone());
                             Ok(Data::new(data::bool::Bool(true)))
                         }
                     }),
@@ -277,15 +272,14 @@ impl Config {
                     run: Arc::new(|a, _i| {
                         let tuple = a.get();
                         let tuple = tuple.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                        let index = tuple.0[1].get().as_any().downcast_ref::<data::int::Int>().unwrap().0 as usize;
-                            let list = tuple.0[0]
-                            .get();
+                        let index = tuple.0[1].read().get().as_any().downcast_ref::<data::int::Int>().unwrap().0 as usize;
+                            let list = tuple.0[0].read();
+                            let list = list.get();
                             let mut list = list
                             .as_any()
                             .downcast_ref::<data::reference::Reference>()
                             .unwrap()
-                            .0
-                            .write().unwrap();
+                            .write();
                             let mut list = list
                             .get_mut();
                             let list = list
@@ -293,7 +287,7 @@ impl Config {
                             .downcast_mut::<List>()
                             .unwrap();
                         if index < list.0.len() {
-                            Ok(Data::one_tuple(std::mem::replace(&mut list.0[index], tuple.0[2].clone())))
+                            Ok(Data::one_tuple(std::mem::replace(&mut list.0[index], tuple.0[2].read().clone())))
                         } else {
                             Ok(Data::empty_tuple())
                         }
@@ -350,15 +344,14 @@ impl Config {
                     run: Arc::new(|a, _i| {
                         let tuple = a.get();
                         let tuple = tuple.as_any().downcast_ref::<data::tuple::Tuple>().unwrap();
-                        let index = tuple.0[1].get().as_any().downcast_ref::<data::int::Int>().unwrap().0 as usize;
-                            let list = tuple.0[0]
-                            .get();
+                        let index = tuple.0[1].read().get().as_any().downcast_ref::<data::int::Int>().unwrap().0 as usize;
+                            let list = tuple.0[0].read();
+                            let list = list.get();
                             let mut list = list
                             .as_any()
                             .downcast_ref::<data::reference::Reference>()
                             .unwrap()
-                            .0
-                            .write().unwrap();
+                            .write();
                             let mut list = list
                             .get_mut();
                             let list = list
diff --git a/mers_lib/src/program/configs/with_math.rs b/mers_lib/src/program/configs/with_math.rs
index 2f8917a..103d907 100755
--- a/mers_lib/src/program/configs/with_math.rs
+++ b/mers_lib/src/program/configs/with_math.rs
@@ -805,7 +805,7 @@ fn func_math_op(
                     .map(|v| &v.0)
                     .filter(|v| v.len() == 2)
                 {
-                    let (a, b) = (&a[0], &a[1]);
+                    let (a, b) = (&a[0].read(), &a[1].read());
                     let (a, b) = (a.get(), b.get());
                     let a = a
                         .as_any()
diff --git a/mers_lib/src/program/run/block.rs b/mers_lib/src/program/run/block.rs
index 22ba127..4d96a1a 100755
--- a/mers_lib/src/program/run/block.rs
+++ b/mers_lib/src/program/run/block.rs
@@ -30,7 +30,7 @@ impl MersStatement for Block {
             .iter()
             .map(|s| s.run(info))
             .last()
-            .unwrap_or_else(|| Ok(Data::new(data::tuple::Tuple(vec![]))))
+            .unwrap_or_else(|| Ok(Data::new(data::tuple::Tuple::empty())))
     }
     fn has_scope(&self) -> bool {
         true
diff --git a/mers_lib/src/program/run/field_chain.rs b/mers_lib/src/program/run/field_chain.rs
index e3930b1..9457b43 100644
--- a/mers_lib/src/program/run/field_chain.rs
+++ b/mers_lib/src/program/run/field_chain.rs
@@ -95,7 +95,7 @@ impl MersStatement for FieldChain {
                     .as_any()
                     .downcast_ref::<data::reference::Reference>()
                 {
-                    obj_ref = r.0.read().unwrap();
+                    obj_ref = r.read();
                     obj_in_ref = obj_ref.get();
                     obj_in_ref.as_any().downcast_ref::<data::object::Object>()
                 } else {
@@ -126,7 +126,7 @@ impl MersStatement for FieldChain {
             for res in more_args.iter().map(|arg| arg.run(info)) {
                 args.push(res?);
             }
-            Data::new(Tuple(args))
+            Data::new(Tuple::from(args))
         } else {
             object
         };
diff --git a/mers_lib/src/program/run/object.rs b/mers_lib/src/program/run/object.rs
index e552583..d95d04f 100644
--- a/mers_lib/src/program/run/object.rs
+++ b/mers_lib/src/program/run/object.rs
@@ -1,7 +1,7 @@
-use std::collections::HashMap;
+use std::{collections::HashMap, sync::Arc};
 
 use crate::{
-    data::{self, object::ObjectT, Data, Type},
+    data::{self, object::ObjectT, reference::ReferenceT, Data, Type},
     errors::{CheckError, EColor, SourceRange},
 };
 
@@ -23,7 +23,19 @@ impl MersStatement for Object {
             init_to_is_empty_type = init_to.types.is_empty();
             let print_is_part_of = init_to.types.len() > 1;
             let mut init_fields = HashMap::new();
-            for t in init_to.types.iter() {
+            for (t, init_to_ref) in init_to
+                .types
+                .iter()
+                .filter_map(|t| t.as_any().downcast_ref::<ReferenceT>())
+                .flat_map(|r| r.0.types.iter().map(|t| (t, true)))
+                .chain(
+                    init_to
+                        .types
+                        .iter()
+                        .filter(|t| !t.as_any().is::<ReferenceT>())
+                        .map(|t| (t, false)),
+                )
+            {
                 if let Some(ot) = t.as_any().downcast_ref::<ObjectT>() {
                     let mut fields = self.fields.iter().map(|(t, _)| *t).collect::<Vec<_>>();
                     fields.sort();
@@ -31,10 +43,12 @@ impl MersStatement for Object {
                         if let Ok(i) = fields.binary_search(field) {
                             fields.remove(i);
                         }
-                        init_fields
-                            .entry(*field)
-                            .or_insert_with(Type::empty)
-                            .add_all(t);
+                        let init_fields = init_fields.entry(*field).or_insert_with(Type::empty);
+                        if init_to_ref {
+                            init_fields.add(Arc::new(ReferenceT(t.clone())));
+                        } else {
+                            init_fields.add_all(t);
+                        }
                     }
                     if !fields.is_empty() {
                         return Err(CheckError::new().msg(vec![
@@ -136,7 +150,7 @@ impl MersStatement for Object {
             self.fields
                 .iter()
                 .map(|(n, s)| Ok::<_, CheckError>((n.clone(), s.run(info)?)))
-                .collect::<Result<_, _>>()?,
+                .collect::<Result<Vec<_>, _>>()?,
         )))
     }
     fn has_scope(&self) -> bool {
diff --git a/mers_lib/src/program/run/tuple.rs b/mers_lib/src/program/run/tuple.rs
index ae19a51..0360789 100755
--- a/mers_lib/src/program/run/tuple.rs
+++ b/mers_lib/src/program/run/tuple.rs
@@ -1,7 +1,7 @@
-use std::collections::VecDeque;
+use std::{collections::VecDeque, sync::Arc};
 
 use crate::{
-    data::{self, tuple::TupleT, Data, MersType, Type},
+    data::{self, reference::ReferenceT, tuple::TupleT, Data, MersType, Type},
     errors::{CheckError, EColor, SourceRange},
 };
 
@@ -23,11 +23,27 @@ impl MersStatement for Tuple {
                 .map(|_| Type::empty())
                 .collect::<VecDeque<_>>();
             let print_is_part_of = init_to.types.len() > 1;
-            for t in init_to.types.iter() {
+            for (t, init_to_ref) in init_to
+                .types
+                .iter()
+                .filter_map(|t| t.as_any().downcast_ref::<ReferenceT>())
+                .flat_map(|r| r.0.types.iter().map(|t| (t, true)))
+                .chain(
+                    init_to
+                        .types
+                        .iter()
+                        .filter(|t| !t.as_any().is::<ReferenceT>())
+                        .map(|t| (t, false)),
+                )
+            {
                 if let Some(t) = t.as_any().downcast_ref::<TupleT>() {
                     if t.0.len() == self.elems.len() {
                         for (i, e) in t.0.iter().enumerate() {
-                            vec[i].add_all(&e);
+                            if init_to_ref {
+                                vec[i].add(Arc::new(ReferenceT(e.clone())));
+                            } else {
+                                vec[i].add_all(e);
+                            }
                         }
                     } else {
                         return Err(CheckError::new().msg(vec![
@@ -102,11 +118,11 @@ impl MersStatement for Tuple {
         )))
     }
     fn run_custom(&self, info: &mut super::Info) -> Result<Data, CheckError> {
-        Ok(Data::new(data::tuple::Tuple(
+        Ok(Data::new(data::tuple::Tuple::from(
             self.elems
                 .iter()
                 .map(|s| Ok(s.run(info)?))
-                .collect::<Result<_, CheckError>>()?,
+                .collect::<Result<Vec<_>, CheckError>>()?,
         )))
     }
     fn has_scope(&self) -> bool {
diff --git a/mers_lib/src/program/run/variable.rs b/mers_lib/src/program/run/variable.rs
index a38f86c..64f370f 100755
--- a/mers_lib/src/program/run/variable.rs
+++ b/mers_lib/src/program/run/variable.rs
@@ -60,14 +60,14 @@ impl MersStatement for Variable {
                 info.scopes[self.var.0].vars[self.var.1] = nothing;
             } else {
                 // (reference to) data which will never be referenced again
-                return Ok(Data::new(data::reference::Reference(Arc::new(
-                    RwLock::new(Data::empty_tuple()),
-                ))));
+                return Ok(Data::new(data::reference::Reference::from(
+                    Data::empty_tuple(),
+                )));
             }
         }
         Ok(if self.is_ref_not_ignore {
             let v = &info.scopes[self.var.0].vars[self.var.1];
-            Data::new(data::reference::Reference(Arc::clone(v)))
+            Data::new(data::reference::Reference::raw(Arc::clone(v)))
         } else {
             info.scopes[self.var.0].vars[self.var.1]
                 .write()
diff --git a/merslsp/Cargo.toml b/merslsp/Cargo.toml
index 63bfd3c..5122d3d 100644
--- a/merslsp/Cargo.toml
+++ b/merslsp/Cargo.toml
@@ -4,7 +4,7 @@ version = "0.9.15"
 edition = "2021"
 
 [dependencies]
-mers_lib = "0.9.18"
+mers_lib = "0.9.28"
 lspower = "1.5.0"
 tokio = { version = "1.36.0", features = ["full"] }
 line-span = "0.1.5"