diff --git a/talc-lang/src/chunk.rs b/talc-lang/src/chunk.rs
index d16581f..adeafdf 100644
--- a/talc-lang/src/chunk.rs
+++ b/talc-lang/src/chunk.rs
@@ -174,7 +174,7 @@ pub struct Catch {
 	pub types: Option<Vec<Symbol>>,
 }
 
-#[derive(Clone, Debug, Default)]
+#[derive(Clone, Debug)]
 pub struct TryTable {
 	pub catches: Vec<Catch>,
 	pub local_count: usize,
diff --git a/talc-lang/src/value/exception.rs b/talc-lang/src/exception.rs
similarity index 84%
rename from talc-lang/src/value/exception.rs
rename to talc-lang/src/exception.rs
index 37e08e7..67174a0 100644
--- a/talc-lang/src/value/exception.rs
+++ b/talc-lang/src/exception.rs
@@ -1,6 +1,5 @@
 use std::{rc::Rc, collections::HashMap, cell::RefCell, fmt::Display};
-use super::{HashValue, RcTable, Value};
-use crate::{symbol::{SYM_DATA, SYM_MSG, SYM_TYPE}, symbol::Symbol};
+use crate::{value::{HashValue, Value}, symbol::{SYM_DATA, SYM_MSG, SYM_TYPE}, symbol::Symbol};
 
 pub type Result<T> = std::result::Result<T, Exception>;
 
@@ -52,7 +51,7 @@ impl Exception {
 		}
 	}
 
-	pub fn to_table(self) -> RcTable {
+	pub fn to_table(self) -> Rc<RefCell<HashMap<HashValue, Value>>> {
 		let mut table = HashMap::new();
 		table.insert((*SYM_TYPE).into(), self.ty.into());
 		if let Some(msg) = self.msg {
@@ -78,16 +77,16 @@ impl Display for Exception {
 #[macro_export]
 macro_rules! exception {
 	($exc_ty:expr, $fstr:literal, $($arg:expr),*) => {
-		$crate::value::exception::Exception::new_with_msg(
+		$crate::exception::Exception::new_with_msg(
 			$exc_ty,
 			format!($fstr, $($arg),*).into()
 		)
 	};
 	($exc_ty:expr, $fstr:literal) => {
-		$crate::value::exception::exception!($exc_ty, $fstr,)
+		$crate::exception::exception!($exc_ty, $fstr,)
 	};
 	($exc_ty:expr) => {
-		$crate::value::exception::Exception::new($exc_ty)
+		$crate::exception::Exception::new($exc_ty)
 	};
 }
 
@@ -96,7 +95,7 @@ pub use exception;
 #[macro_export]
 macro_rules! throw {
 	($($args:tt)*) => {
-		return Err($crate::value::exception::exception!($($args)*))
+		return Err($crate::exception::exception!($($args)*))
 	};
 }
 
diff --git a/talc-lang/src/lib.rs b/talc-lang/src/lib.rs
index 5af8d77..6894f9b 100644
--- a/talc-lang/src/lib.rs
+++ b/talc-lang/src/lib.rs
@@ -15,6 +15,7 @@ pub mod symbol;
 
 pub mod ast;
 pub mod value;
+pub mod exception;
 pub mod chunk;
 pub mod compiler;
 
diff --git a/talc-lang/src/symbol.rs b/talc-lang/src/symbol.rs
index 9a941b6..021c2a4 100644
--- a/talc-lang/src/symbol.rs
+++ b/talc-lang/src/symbol.rs
@@ -24,6 +24,8 @@ lazy_static! {
 	pub static ref SYM_FUNCTION: Symbol = symbol!(function);
 	pub static ref SYM_NATIVE_FUNC: Symbol = symbol!(native_func);
 
+	pub static ref SYM_END_ITERATION: Symbol = symbol!(end_iteration);
+
 	pub static ref SYM_TYPE: Symbol = symbol!(type);
 	pub static ref SYM_MSG: Symbol = symbol!(msg);
 	pub static ref SYM_DATA: Symbol = symbol!(data);
diff --git a/talc-lang/src/value/function.rs b/talc-lang/src/value/function.rs
index f3bd7ae..afdda20 100644
--- a/talc-lang/src/value/function.rs
+++ b/talc-lang/src/value/function.rs
@@ -1,8 +1,8 @@
 use std::rc::Rc;
 
-use crate::{chunk::Chunk, Vm};
+use crate::{chunk::Chunk, Vm, exception::Result};
 
-use super::{Value, exception::Result};
+use super::{Value};
 
 #[derive(Clone, Copy, Debug, Default)]
 pub struct FuncAttrs {
@@ -10,7 +10,7 @@ pub struct FuncAttrs {
 	pub variadic: bool,
 }
 
-#[derive(Debug, Default)]
+#[derive(Debug)]
 pub struct Function {
 	pub attrs: FuncAttrs,
 	pub chunk: Rc<Chunk>,
diff --git a/talc-lang/src/value/index.rs b/talc-lang/src/value/index.rs
index 6ff51ef..3397562 100644
--- a/talc-lang/src/value/index.rs
+++ b/talc-lang/src/value/index.rs
@@ -1,6 +1,6 @@
-use crate::{symbol::{SYM_INDEX_ERROR, SYM_TYPE_ERROR}, value::{cell_take, function::NativeFunc}, vmcalliter, Vm};
+use crate::{symbol::{SYM_END_ITERATION, SYM_INDEX_ERROR, SYM_TYPE_ERROR}, value::function::NativeFunc, vmcalliter, Vm, exception::{Result, throw}};
 
-use super::{Value, exception::{Result, throw}, range::RangeType};
+use super::{Value, range::RangeType};
 
 impl Value {
 	pub fn index(&self, idx: Self) -> Result<Self> {
@@ -34,8 +34,8 @@ impl Value {
 				let col = col.clone();
 				let func = move |vm: &mut Vm, _| {
 					match vmcalliter!(vm; ii.clone())? {
-						Some(i) => Ok(col.index(cell_take(i))?.to_cell()),
-						None => Ok(Value::Nil)
+						Some(i) => Ok(col.index(i)?.to_cell()),
+						None => Ok(Value::from(*SYM_END_ITERATION)),
 					}
 				};
 				Ok(NativeFunc::new(Box::new(func), 0).into())
@@ -67,7 +67,7 @@ impl Value {
 				let iter = val.to_iter_function()?;
 				let mut vals = Vec::new();
 				while let Some(v) = vmcalliter!(vm; iter.clone())? {
-					vals.push(cell_take(v));
+					vals.push(v);
 				}
 				let mut tm = t.borrow_mut();
 				match r.ty {
@@ -114,7 +114,7 @@ impl Value {
 					let Some(v) = vmcalliter!(vm; val.clone())? else {
 						throw!(*SYM_INDEX_ERROR, "not enough values provided for store index")
 					};
-					col.store_index(vm, cell_take(i), cell_take(v))?;
+					col.store_index(vm, i, v)?;
 				}
 				Ok(())
 			} else {
diff --git a/talc-lang/src/value/mod.rs b/talc-lang/src/value/mod.rs
index 0a02c5d..cee77e5 100644
--- a/talc-lang/src/value/mod.rs
+++ b/talc-lang/src/value/mod.rs
@@ -4,10 +4,10 @@ pub use num_complex::Complex64;
 pub use num_rational::Rational64;
 
 use crate::symbol::{Symbol, SYM_HASH_ERROR};
+use crate::exception::{Exception, throw};
 
-use self::{range::{Range, RangeType}, function::{Function, NativeFunc}, exception::{Exception, throw}};
+use self::{range::{Range, RangeType}, function::{Function, NativeFunc}};
 
-pub mod exception;
 pub mod function;
 pub mod ops;
 pub mod range;
@@ -207,8 +207,3 @@ impl_from!(String, String, into);
 impl_from!(&str, String, into);
 impl_from!(Box<str>, String, into);
 impl_from!(RefCell<Value>, Cell, rc);
-
-#[inline]
-pub fn cell_take<T: Clone>(cell: Rc<RefCell<T>>) -> T {
-	Rc::unwrap_or_clone(cell).into_inner()
-}
diff --git a/talc-lang/src/value/ops.rs b/talc-lang/src/value/ops.rs
index 76d5e34..80c2836 100644
--- a/talc-lang/src/value/ops.rs
+++ b/talc-lang/src/value/ops.rs
@@ -3,9 +3,9 @@ use std::{cell::RefCell, cmp::Ordering, ops::{Add, Div, Mul, Neg, Sub}, rc::Rc};
 use num_complex::Complex64;
 use num_rational::Rational64;
 
-use crate::{symbol::SYM_TYPE_ERROR, value::range::RangeType, Vm};
+use crate::{exception::{throw, Result}, symbol::{SYM_END_ITERATION, SYM_TYPE_ERROR}, value::range::RangeType, Vm};
 
-use super::{exception::{throw, Result}, function::{FuncAttrs, NativeFunc}, range::Range, HashValue, Value};
+use super::{function::{FuncAttrs, NativeFunc}, range::Range, HashValue, Value};
 
 impl Value {
 	pub fn truthy(&self) -> bool {
@@ -178,8 +178,8 @@ impl Value {
 			return Ok(V::Ratio(rpow(*(*x).numer(), *(*x).denom(), *y)?.into()));
 		}
 		match promote(self, rhs) {
-			(V::Int(x), V::Int(y))
-				=> Ok(V::Ratio(rpow(x, 1, y)?.into())),
+			(V::Int(x), V::Int(y)) if y >= 0 => Ok(V::Int(ipow(x, y as u64)?)),
+			(V::Int(x), V::Int(y)) => Ok(V::Ratio(rpow(x, 1, y)?.into())),
 			(V::Float(x), V::Float(y))
 				=> Ok(V::Float(x.powf(y))),
 			(V::Ratio(x), V::Ratio(y))
@@ -319,20 +319,19 @@ impl Value {
 		Value::Cell(Rc::new(RefCell::new(self)))
 	}
 
-	pub fn iter_unpack(self) -> Result<Option<Rc<RefCell<Self>>>> {
+	pub fn iter_unpack(self) -> Option<Self> {
 		match self {
-			Self::Nil => Ok(None),
-			Self::Cell(v) => Ok(Some(v)),
-			_ => throw!(*SYM_TYPE_ERROR, "expected iterator to return cell or nil")
+			Self::Symbol(s) if s == *SYM_END_ITERATION => None,
+			v => Some(v),
 		}
 	}
 
-	pub fn iter_pack(v: Option<Self>) -> Self {
-		match v {
-			Some(v) => v.to_cell(),
-			None => Value::Nil,
-		}
-	}
+    pub fn iter_pack(v: Option<Self>) -> Self {
+        match v {
+            Some(v) => v,
+            None => Value::from(*SYM_END_ITERATION)
+        }
+    }
 
 	pub fn to_iter_function(self) -> Result<Self> {
 		match self {
@@ -340,11 +339,8 @@ impl Value {
 			Self::Range(range) => {
 				let range_iter = RefCell::new(range.into_iter());
 				let f = move |_: &mut Vm, _: Vec<Value>| -> Result<Value> {
-					if let Some(v) = range_iter.borrow_mut().next() {
-						Ok(Value::from(v).to_cell())
-					} else {
-						Ok(Value::Nil)
-					}
+					Ok(Value::iter_pack(range_iter.borrow_mut().next()
+                        .map(Value::from)))
 				};
 				Ok(NativeFunc::new(Box::new(f), 0).into())
 			},
@@ -354,9 +350,9 @@ impl Value {
 					let pos = *byte_pos.borrow();
 					if let Some(v) = &s[pos..].chars().next() {
 						*byte_pos.borrow_mut() += v.len_utf8();
-						Ok(Value::from(v.to_string()).to_cell())
+						Ok(Value::from(v.to_string()))
 					} else {
-						Ok(Value::Nil)
+						Ok(Value::from(*SYM_END_ITERATION))
 					}
 				};
 				Ok(NativeFunc::new(Box::new(f), 0).into())
@@ -367,9 +363,9 @@ impl Value {
 					let i = *idx.borrow();
 					if let Some(v) = list.borrow().get(i) {
 						*idx.borrow_mut() += 1;
-						Ok(v.clone().to_cell())
+						Ok(v.clone())
 					} else {
-						Ok(Value::Nil)
+						Ok(Value::from(*SYM_END_ITERATION))
 					}
 				};
 				Ok(NativeFunc::new(Box::new(f), 0).into())
@@ -378,11 +374,8 @@ impl Value {
 				let keys: Vec<HashValue> = table.borrow().keys().cloned().collect();
 				let keys = RefCell::new(keys.into_iter());
 				let f = move |_: &mut Vm, _: Vec<Value>| -> Result<Value> {
-					if let Some(v) = keys.borrow_mut().next() {
-						Ok(v.into_inner().to_cell())
-					} else {
-						Ok(Value::Nil)
-					}
+					Ok(Value::iter_pack(keys.borrow_mut().next()
+                        .map(HashValue::into_inner)))
 				};
 				Ok(NativeFunc::new(Box::new(f), 0).into())
 			},
diff --git a/talc-lang/src/vm.rs b/talc-lang/src/vm.rs
index 40b0cb0..658876c 100644
--- a/talc-lang/src/vm.rs
+++ b/talc-lang/src/vm.rs
@@ -1,10 +1,9 @@
 use std::{cmp::Ordering, collections::HashMap, rc::Rc, sync::{atomic::AtomicBool, Arc}};
 
-use crate::{ast::{BinaryOp, UnaryOp}, chunk::Instruction, symbol::{Symbol, SYM_CALL_STACK_OVERFLOW, SYM_INTERRUPTED, SYM_NAME_ERROR, SYM_TYPE_ERROR}, value::{cell_take, exception::{throw, Exception, Result}, function::{FuncAttrs, Function, NativeFunc}, Value}};
+use crate::{ast::{BinaryOp, UnaryOp}, chunk::Instruction, symbol::{Symbol, SYM_CALL_STACK_OVERFLOW, SYM_INTERRUPTED, SYM_NAME_ERROR, SYM_TYPE_ERROR}, value::{function::{FuncAttrs, Function, NativeFunc}, Value}, exception::{throw, Exception, Result}};
 
 struct TryFrame { idx: usize, stack_len: usize }
 
-#[derive(Default)]
 struct CallFrame {
 	func: Rc<Function>,
 	locals: Vec<Value>,
@@ -18,7 +17,9 @@ impl CallFrame {
 		Self {
 			func,
 			locals,
-			..Self::default()
+            try_frames: Vec::new(),
+            ip: 0,
+            root: false,
 		}
 	}
 }
@@ -92,7 +93,8 @@ fn get_call_outcome(mut args: Vec<Value>) -> Result<CallOutcome> {
 					.expect("did not receive vararg") else {
 					panic!("did not receive vararg")
 				};
-				args.extend(cell_take(varargs));
+                let varargs = Rc::unwrap_or_clone(varargs).take();
+				args.extend(varargs);
 			}
 			vm.call_value(f.clone(), args)
 		};
@@ -366,13 +368,12 @@ impl Vm {
 			// [i,cell(v)] -> [i,v]
 			// [i,nil] -> [], ip = n
 			I::IterTest(n) => {
-				match self.pop() {
-					Value::Cell(c) => self.push(cell_take(c)),
-					Value::Nil => {
+				match self.pop().iter_unpack() {
+					Some(v) => self.push(v),
+					None => {
 						self.pop();
 						frame.ip = usize::from(n)
 					},
-					v => throw!(*SYM_TYPE_ERROR, "iterator returned invalid value {v}")
 				}
 			},
 			// try_frames.push(t, stack.len())
@@ -404,20 +405,27 @@ impl Vm {
 				if let Value::NativeFunc(nf) = &args[0] {
 					let nf = nf.clone();
 
-					// safety: frame is restored immediately after
-					// function call ends
-					// ~25% performance improvement in for loop-heavy code
+					// safety: frame is restored immediately
+					// after function call ends
+					// ~25% performance improvement in 
+                    // code heavy on native function calls
 					unsafe {
 						let f = std::ptr::read(frame);
 						self.call_stack.push(f);
 					}
 
-					let res = (nf.func)(self, args)?;
+					let res = (nf.func)(self, args);
 
-					unsafe {
-						let f = self.call_stack.pop().expect("no frame to pop");
-						std::ptr::write(frame, f);
-					}
+                    // safety: frame was referencing invalid memory due to
+                    // previous unsafe block, write will fix that
+                    unsafe {
+                        let f = self.call_stack.pop().expect("no frame to pop");
+                        std::ptr::write(frame, f);
+                    }
+
+                    // make sure we restored the value of frame
+                    // before propagating exceptions
+                    let res = res?;
 
 					self.stack.push(res);
 				} else if let Value::Function(func) = &args[0] {
@@ -465,6 +473,6 @@ macro_rules! vmcall {
 #[macro_export]
 macro_rules! vmcalliter {
 	($($input:tt)*) => {
-		$crate::vmcall!($($input)*).and_then(|v| v.iter_unpack())
+		$crate::vmcall!($($input)*).map(|v| v.iter_unpack())
 	}
 }
diff --git a/talc-std/src/collection.rs b/talc-std/src/collection.rs
index a5a6442..2d862c3 100644
--- a/talc-std/src/collection.rs
+++ b/talc-std/src/collection.rs
@@ -1,6 +1,6 @@
 use std::cmp::Ordering;
 
-use talc_lang::{exception, symbol::SYM_TYPE_ERROR, throw, value::{exception::Result, function::NativeFunc, Value}, vmcall, Vm};
+use talc_lang::{exception, exception::Result, symbol::SYM_TYPE_ERROR, throw, value::{function::NativeFunc, Value}, vmcall, Vm};
 use talc_macros::native_func;
 
 use crate::unpack_args;
diff --git a/talc-std/src/exception.rs b/talc-std/src/exception.rs
index d784c98..ebf159b 100644
--- a/talc-std/src/exception.rs
+++ b/talc-std/src/exception.rs
@@ -1,4 +1,4 @@
-use talc_lang::{symbol::SYM_TYPE_ERROR, value::{exception::{throw, Exception, Result}, Value}, Vm};
+use talc_lang::{symbol::SYM_TYPE_ERROR, exception::{throw, Exception, Result}, value::Value, Vm};
 use talc_macros::native_func;
 
 use crate::{unpack_args, unpack_varargs};
diff --git a/talc-std/src/io.rs b/talc-std/src/io.rs
index a5124c9..b256ed9 100644
--- a/talc-std/src/io.rs
+++ b/talc-std/src/io.rs
@@ -1,6 +1,6 @@
 use std::{io::Write, time::{SystemTime, UNIX_EPOCH}};
 
-use talc_lang::{value::{exception::{throw, Result}, Value}, vmcall, Vm};
+use talc_lang::{value::Value, vmcall, Vm, exception::{throw, Result}};
 use talc_macros::native_func;
 
 use crate::{unpack_args, SYM_IO_ERROR};
@@ -33,13 +33,7 @@ pub fn readln(_: &mut Vm, _: Vec<Value>) -> Result<Value> {
 #[native_func(0)]
 pub fn time(_: &mut Vm, _: Vec<Value>) -> Result<Value> {
 	let time = SystemTime::now().duration_since(UNIX_EPOCH).expect("time went backwards");
-	Ok((time.as_secs() as i64).into())
-}
-
-#[native_func(0)]
-pub fn time_ms(_: &mut Vm, _: Vec<Value>) -> Result<Value> {
-	let time = SystemTime::now().duration_since(UNIX_EPOCH).expect("time went backwards");
-	Ok((time.as_millis() as i64).into())
+	Ok(time.as_secs_f64().into())
 }
 
 #[native_func(0)]
@@ -55,7 +49,7 @@ pub fn time_fn(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	vmcall!(vm; func)?;
 	let tf = SystemTime::now();
 	let time = tf.duration_since(t0).expect("time went backwards");
-	Ok((time.as_nanos() as i64).into())
+	Ok((time.as_secs_f64() as i64).into())
 }
 
 pub fn load(vm: &mut Vm) {
@@ -64,7 +58,6 @@ pub fn load(vm: &mut Vm) {
 	vm.set_global_name("readln", readln().into());
 
 	vm.set_global_name("time", time().into());
-	vm.set_global_name("time_ms", time_ms().into());
 	vm.set_global_name("time_ns", time_ns().into());
 	vm.set_global_name("time_fn", time_fn().into());
 }
diff --git a/talc-std/src/iter.rs b/talc-std/src/iter.rs
index 10c7feb..d168513 100644
--- a/talc-std/src/iter.rs
+++ b/talc-std/src/iter.rs
@@ -1,6 +1,6 @@
 use std::{cell::RefCell, collections::HashMap, rc::Rc};
 
-use talc_lang::{symbol::SYM_TYPE_ERROR, throw, value::{cell_take, exception::Result, function::NativeFunc, range::RangeType, HashValue, Value}, vmcall, vmcalliter, Vm};
+use talc_lang::{symbol::SYM_TYPE_ERROR, exception::Result, throw, value::{function::NativeFunc, range::RangeType, HashValue, Value}, vmcall, vmcalliter, Vm};
 use talc_macros::native_func;
 
 use crate::{unpack_args, unpack_varargs};
@@ -11,14 +11,12 @@ pub fn load(vm: &mut Vm) {
 	vm.set_global_name("pairs", pairs().into());
 	vm.set_global_name("once", once().into());
 	vm.set_global_name("forever", forever().into());
-	vm.set_global_name("do_forever", forever().into());
 
 	// modify
 	vm.set_global_name("map", map().into());
 	vm.set_global_name("scan", scan().into());
 	vm.set_global_name("tee", tee().into());
 	vm.set_global_name("filter", filter().into());
-	vm.set_global_name("filter_map", filter_map().into());
 	vm.set_global_name("take", take().into());
 	vm.set_global_name("skip", skip().into());
 	vm.set_global_name("enumerate", enumerate().into());
@@ -76,9 +74,9 @@ pub fn pairs(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let f = move |_: &mut Vm, _: Vec<Value>| -> Result<Value> {
 		if let Some(k) = keys.borrow_mut().next() {
 			let v = table.borrow().get(&k).cloned().unwrap_or(Value::Nil);
-			Ok(Value::from(vec![k.into_inner(), v]).to_cell())
+			Ok(Value::from(vec![k.into_inner(), v]))
 		} else {
-			Ok(Value::Nil)
+			Ok(Value::iter_pack(None))
 		}
 	};
 	Ok(NativeFunc::new(Box::new(f), 0).into())
@@ -90,11 +88,7 @@ pub fn once(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 	let v = RefCell::new(Some(val));
 	let f = move |_: &mut Vm, _| {
-		if let Some(v) = v.borrow_mut().take() {
-			Ok(v.to_cell())
-		} else {
-			Ok(Value::Nil)
-		}
+		Ok(Value::iter_pack(v.borrow_mut().take()))
 	};
 	Ok(NativeFunc::new(Box::new(f), 0).into())
 }
@@ -104,17 +98,7 @@ pub fn forever(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let [_, val] = unpack_args!(args);
 
 	let f = move |_: &mut Vm, _| {
-		Ok(val.clone().to_cell())
-	};
-	Ok(NativeFunc::new(Box::new(f), 0).into())
-}
-
-#[native_func(1)]
-pub fn do_forever(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
-	let [_, func] = unpack_args!(args);
-
-	let f = move |vm: &mut Vm, _| {
-		Ok(vmcall!(vm; func.clone())?.to_cell())
+		Ok(val.clone())
 	};
 	Ok(NativeFunc::new(Box::new(f), 0).into())
 }
@@ -132,8 +116,8 @@ pub fn map(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 	let f = move |vm: &mut Vm, _| {
 		match vmcalliter!(vm; iter.clone())? {
-			Some(val) => Ok(vmcall!(vm; map.clone(), cell_take(val))?.to_cell()),
-			None => Ok(Value::Nil),
+			Some(val) => Ok(vmcall!(vm; map.clone(), val)?),
+			None => Ok(Value::iter_pack(None)),
 		}
 	};
 	Ok(NativeFunc::new(Box::new(f), 0).into())
@@ -147,10 +131,10 @@ pub fn tee(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let f = move |vm: &mut Vm, _| {
 		match vmcalliter!(vm; iter.clone())? {
 			Some(val) => {
-				vmcall!(vm; tee.clone(), cell_take(val.clone()))?;
+				vmcall!(vm; tee.clone(), val.clone())?;
 				Ok(val.into())
 			}
-			None => Ok(Value::Nil),
+			None => Ok(Value::iter_pack(None)),
 		}
 	};
 	Ok(NativeFunc::new(Box::new(f), 0).into())
@@ -163,18 +147,13 @@ pub fn scan(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 	let result = RefCell::new(init);
 	let f = move |vm: &mut Vm, _| {
-		match vmcalliter!(vm; iter.clone())? {
-			Some(val) => {
-				let val = cell_take(val);
-				let r = vmcall!(vm; func.clone(), result.take(), val)?;
-				*result.borrow_mut() = r.clone();
-				Ok(r.to_cell())
-			},
-			None => {
-				result.take();
-				Ok(Value::Nil)
-			},
-		}
+		let Some(val) = vmcalliter!(vm; iter.clone())? else {
+            result.take();
+            return Ok(Value::iter_pack(None))
+        };
+        let r = vmcall!(vm; func.clone(), result.take(), val)?;
+        *result.borrow_mut() = r.clone();
+        Ok(r)
 	};
 	Ok(NativeFunc::new(Box::new(f), 0).into())
 }
@@ -186,11 +165,10 @@ pub fn filter(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 	let f = move |vm: &mut Vm, _| {
 		loop {
-			let next = match vmcalliter!(vm; iter.clone())? {
-				Some(next) => next,
-				None => return Ok(Value::Nil),
+			let Some(next) = vmcalliter!(vm; iter.clone())? else {
+				return Ok(Value::iter_pack(None))
 			};
-			let res = vmcall!(vm; filter.clone(), cell_take(next.clone()))?;
+			let res = vmcall!(vm; filter.clone(), next.clone())?;
 			if res.truthy() {
 				return Ok(next.into())
 			}
@@ -199,26 +177,6 @@ pub fn filter(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	Ok(NativeFunc::new(Box::new(f), 0).into())
 }
 
-#[native_func(2)]
-pub fn filter_map(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
-	let [_, fmap, iter] = unpack_args!(args);
-	let iter = iter.to_iter_function()?;
-
-	let f = move |vm: &mut Vm, _| {
-		loop {
-			let next = match vmcalliter!(vm; iter.clone())? {
-				Some(next) => next,
-				None => return Ok(Value::Nil),
-			};
-			let res = vmcall!(vm; fmap.clone(), cell_take(next))?;
-			if let Value::Cell(_) = res {
-				return Ok(res)
-			}
-		}
-	};
-	Ok(NativeFunc::new(Box::new(f), 0).into())
-}
-
 #[native_func(2)]
 pub fn take(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let [_, count, iter] = unpack_args!(args);
@@ -233,14 +191,11 @@ pub fn take(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let taken = RefCell::new(0);
 	let f = move |vm: &mut Vm, _| {
 		if *taken.borrow() >= count {
-			return Ok(Value::Nil)
+			return Ok(Value::iter_pack(None))
 		}
-		let next = match vmcalliter!(vm; iter.clone())? {
-			Some(next) => next,
-			None => {
-				*taken.borrow_mut() = count;
-				return Ok(Value::Nil)
-			}
+		let Some(next) = vmcalliter!(vm; iter.clone())? else {
+            *taken.borrow_mut() = count;
+            return Ok(Value::iter_pack(None))
 		};
 		*taken.borrow_mut() += 1;
 		Ok(next.into())
@@ -280,14 +235,13 @@ pub fn enumerate(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 	let counter = RefCell::new(0);
 	let f = move |vm: &mut Vm, _| {
-		let next = match vmcalliter!(vm; iter.clone())? {
-			Some(next) => cell_take(next),
-			None => return Ok(Value::Nil),
+		let Some(next) = vmcalliter!(vm; iter.clone())? else {
+			return Ok(Value::iter_pack(None))
 		};
 		let mut c = counter.borrow_mut();
 		let n = *c;
 		*c += 1;
-		Ok(Value::from(vec![n.into(), next]).to_cell())
+		Ok(Value::from(vec![n.into(), next]))
 	};
 
 	Ok(NativeFunc::new(Box::new(f), 0).into())
@@ -299,12 +253,12 @@ pub fn cycle(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let [_, iter] = unpack_args!(args);
 	let iter = iter.to_iter_function()?;
 
-	let record = RefCell::new((Vec::<Rc<RefCell<Value>>>::new(), false, 0));
+	let record = RefCell::new((Vec::<Value>::new(), false, 0));
 	let f = move |vm: &mut Vm, _| {
 		if record.borrow().1 {
 			let mut r = record.borrow_mut();
 			if r.0.is_empty() {
-				return Ok(Value::Nil)
+				return Ok(Value::iter_pack(None))
 			}
 			let val = r.0[r.2].clone();
 			r.2 = (r.2 + 1) % r.0.len();
@@ -319,7 +273,7 @@ pub fn cycle(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 				let mut r = record.borrow_mut();
 				r.1 = true;
 				if r.0.is_empty() {
-					Ok(Value::Nil)
+					Ok(Value::iter_pack(None))
 				} else {
 					r.2 = (r.2 + 1) % r.0.len();
 					Ok(r.0[0].clone().into())
@@ -350,25 +304,23 @@ pub fn step(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let state = RefCell::new(Step::First);
 	let f = move |vm: &mut Vm, _| match state.take() {
 		Step::First => {
-			match vmcalliter!(vm; iter.clone())? {
-				Some(x) => {
-					*state.borrow_mut() = Step::Going;
-					Ok(x.into())
-				},
-				None => Ok(Value::Nil),
-			}
+			let res = vmcalliter!(vm; iter.clone())?;
+            if res.is_some() {
+                *state.borrow_mut() = Step::Going;
+            }
+            Ok(Value::iter_pack(res))
 		},
 		Step::Going => {
 			for _ in 0..(by-1) {
 				if vmcall!(vm; iter.clone())? == Value::Nil {
-					return Ok(Value::Nil)
+                    return Ok(Value::iter_pack(None))
 				}
 			}
 			let Some(x) = vmcalliter!(vm; iter.clone())? else {
-				return Ok(Value::Nil)
+				return Ok(Value::iter_pack(None))
 			};
 			*state.borrow_mut() = Step::Going;
-			Ok(x.into())
+			Ok(x)
 		},
 		Step::End => Ok(Value::Nil),
 	};
@@ -385,15 +337,11 @@ pub fn rev(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 		if lst.borrow().is_none() {
 			let mut l = Vec::new();
 			while let Some(x) = vmcalliter!(vm; iter.clone())? {
-				l.push(cell_take(x))
+				l.push(x)
 			}
-			l.reverse();
-			*lst.borrow_mut() = Some(l.into_iter());
-		}
-		match lst.borrow_mut().as_mut().unwrap().next() {
-			Some(v) => Ok(v.to_cell()),
-			None => Ok(Value::Nil),
+			*lst.borrow_mut() = Some(l);
 		}
+		Ok(Value::iter_pack(lst.borrow_mut().as_mut().unwrap().pop()))
 
 	};
 	Ok(NativeFunc::new(Box::new(f), 0).into())
@@ -417,11 +365,11 @@ pub fn zip(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 		let mut res = Vec::with_capacity(iters.len());
 		for i in iters.iter() {
 			match vmcalliter!(vm; i.clone())? {
-				Some(v) => res.push(cell_take(v)),
-				None => return Ok(Value::Nil),
+				Some(v) => res.push(v),
+				None => return Ok(Value::iter_pack(None)),
 			};
 		}
-		Ok(Value::from(res).to_cell())
+		Ok(Value::from(res))
 	};
 
 	Ok(NativeFunc::new(Box::new(f), 0).into())
@@ -439,16 +387,16 @@ pub fn alternate(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let f = move |vm: &mut Vm, _| {
 		let mut s = state.borrow_mut();
 		if s.1 {
-			return Ok(Value::Nil);
+			return Ok(Value::iter_pack(None));
 		}
 		let n = s.0;
 		s.0 = (s.0 + 1) % iters.len();
 		drop(s);
 		match vmcalliter!(vm; iters[n].clone())? {
-			Some(v) => Ok(v.into()),
+			Some(v) => Ok(v),
 			None => {
 				state.borrow_mut().1 = true;
-				Ok(Value::Nil)
+				Ok(Value::iter_pack(None))
 			}
 		}
 	};
@@ -458,14 +406,13 @@ pub fn alternate(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 #[derive(Default)]
 enum Intersperse {
-	Init, Waiting, HasNext(Rc<RefCell<Value>>), #[default] End
+	Init, Waiting, HasNext(Value), #[default] End
 }
 
 #[native_func(2)]
 pub fn intersperse(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let [_, val, iter] = unpack_args!(args);
 	let iter = iter.to_iter_function()?;
-	let val = val.to_cell();
 
 	let state = RefCell::new(Intersperse::Init);
 	let f = move |vm: &mut Vm, _| {
@@ -473,11 +420,11 @@ pub fn intersperse(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 			Intersperse::Init => match vmcalliter!(vm; iter.clone())? {
 				Some(v) => {
 					*state.borrow_mut() = Intersperse::Waiting;
-					Ok(v.into())
+					Ok(v)
 				},
 				None => {
 					*state.borrow_mut() = Intersperse::End;
-					Ok(Value::Nil)
+					Ok(Value::iter_pack(None))
 				},
 			},
 			Intersperse::Waiting => match vmcalliter!(vm; iter.clone())? {
@@ -487,14 +434,14 @@ pub fn intersperse(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 				},
 				None => {
 					*state.borrow_mut() = Intersperse::End;
-					Ok(Value::Nil)
+					Ok(Value::iter_pack(None))
 				},
 			},
 			Intersperse::HasNext(v) => {
 				*state.borrow_mut() = Intersperse::Waiting;
-				Ok(v.into())
+				Ok(v)
 			},
-			Intersperse::End => Ok(Value::Nil),
+			Intersperse::End => Ok(Value::iter_pack(None)),
 		}
 	};
 
@@ -514,7 +461,7 @@ pub fn chain(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 			return vmcall!(vm; iter2.clone())
 		}
 		match vmcalliter!(vm; iter1.clone())? {
-			Some(v) => Ok(v.into()),
+			Some(v) => Ok(v),
 			None => {
 				*done_first.borrow_mut() = true;
 				vmcall!(vm; iter2.clone())
@@ -551,12 +498,12 @@ pub fn cartprod(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 				let v = vmcalliter!(vm; b.clone())?;
 				let mut s = state.borrow_mut();
 				match v {
-					Some(x) => s.b_data.push(cell_take(x)),
+					Some(x) => s.b_data.push(x),
 					None => {
 						s.b_done = true;
 						if s.b_idx == 0 {
 							s.done = true;
-							return Ok(Value::Nil)
+							return Ok(Value::iter_pack(None))
 						}
 						s.b_idx = 0;
 					}
@@ -574,10 +521,10 @@ pub fn cartprod(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 		if state.borrow().b_idx == 0 {
 			match vmcalliter!(vm; a.clone())? {
-				Some(v) => state.borrow_mut().a_val = cell_take(v),
+				Some(v) => state.borrow_mut().a_val = v,
 				None => {
 					state.borrow_mut().done = true;
-					return Ok(Value::Nil)
+					return Ok(Value::iter_pack(None))
 				}
 			}
 		}
@@ -606,7 +553,7 @@ pub fn list(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let iter = iter.to_iter_function()?;
 	let mut result = Vec::new();
 	while let Some(value) = vmcalliter!(vm; iter.clone())? {
-		result.push(cell_take(value));
+		result.push(value);
 	};
 	Ok(result.into())
 }
@@ -617,10 +564,11 @@ pub fn table(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let iter = iter.to_iter_function()?;
 	let mut result = HashMap::new();
 	while let Some(value) = vmcalliter!(vm; iter.clone())? {
-		let Value::List(l) = cell_take(value) else {
+		let Value::List(l) = value else {
 			throw!(*SYM_TYPE_ERROR, "table expected iterator to yield list")
 		};
-		let Ok([k, v]): std::result::Result<[Value; 2], Vec<Value>> = cell_take(l).try_into() else {
+        let l = Rc::unwrap_or_clone(l).take();
+		let Ok([k, v]): std::result::Result<[Value; 2], Vec<Value>> = l.try_into() else {
 			throw!(*SYM_TYPE_ERROR, "table expected iterator to yield list of length 2")
 		};
 		result.insert(k.try_into()?, v);
@@ -653,11 +601,11 @@ pub fn fold(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let iter: Value = iter.to_iter_function()?;
 
 	let mut result = match vmcalliter!(vm; iter.clone())? {
-		Some(v) => cell_take(v),
-		None => return Ok(Value::Nil),
+		Some(v) => v,
+		None => return Ok(Value::iter_pack(None)),
 	};
 	while let Some(value) = vmcalliter!(vm; iter.clone())? {
-		result = vmcall!(vm; func.clone(), result, cell_take(value))?;
+		result = vmcall!(vm; func.clone(), result, value)?;
 	}
 	Ok(result)
 }
@@ -669,7 +617,7 @@ pub fn foldi(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 	let mut result = init;
 	while let Some(value) = vmcalliter!(vm; iter.clone())? {
-		result = vmcall!(vm; func.clone(), result, cell_take(value))?;
+		result = vmcall!(vm; func.clone(), result, value)?;
 	}
 	Ok(result)
 }
@@ -681,7 +629,7 @@ pub fn sum(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 	let mut result = Value::Int(0);
 	while let Some(value) = vmcalliter!(vm; iter.clone())? {
-		result = (result + cell_take(value))?
+		result = (result + value)?
 	}
 	Ok(result)
 }
@@ -693,7 +641,7 @@ pub fn prod(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 
 	let mut result = Value::Int(1);
 	while let Some(value) = vmcalliter!(vm; iter.clone())? {
-		result = (result * cell_take(value))?
+		result = (result * value)?
 	}
 	Ok(result)
 }
@@ -704,7 +652,7 @@ pub fn any(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let iter = iter.to_iter_function()?;
 
 	while let Some(value) = vmcalliter!(vm; iter.clone())? {
-		if RefCell::borrow(&value).truthy() {
+		if value.truthy() {
 			return Ok(true.into())
 		}
 	}
@@ -717,7 +665,7 @@ pub fn all(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let iter = iter.to_iter_function()?;
 
 	while let Some(value) = vmcalliter!(vm; iter.clone())? {
-		if !RefCell::borrow(&value).truthy() {
+		if !value.truthy() {
 			return Ok(false.into())
 		}
 	}
@@ -729,11 +677,11 @@ pub fn last(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let [_, iter] = unpack_args!(args);
 	let iter = iter.to_iter_function()?;
 
-	let mut last = Rc::new(RefCell::new(Value::Nil));
+	let mut last = Value::Nil;
 	while let Some(value) = vmcalliter!(vm; iter.clone())? {
 		last = value;
 	}
-	Ok(cell_take(last))
+	Ok(last)
 }
 
 #[native_func(2)]
@@ -750,7 +698,7 @@ pub fn nth(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 		}
 	}
 	match vmcalliter!(vm; iter)? {
-		Some(v) => Ok(cell_take(v)),
+		Some(v) => Ok(v),
 		None => Ok(Value::Nil),
 	}
 }
@@ -763,7 +711,7 @@ pub fn contains(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	for _ in 0.. {
 		match vmcalliter!(vm; iter.clone())? {
 			None => return Ok(Value::Nil),
-			Some(v) => if *RefCell::borrow(&v) == val {
+			Some(v) => if v == val {
 				return Ok(true.into())
 			}
 		}
@@ -779,7 +727,7 @@ pub fn index_of(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	for i in 0.. {
 		match vmcalliter!(vm; iter.clone())? {
 			None => return Ok(Value::Nil),
-			Some(v) => if *RefCell::borrow(&v) == val {
+			Some(v) => if v == val {
 				return Ok(i.into())
 			}
 		}
@@ -795,7 +743,7 @@ pub fn index_if(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	for i in 0.. {
 		match vmcalliter!(vm; iter.clone())? {
 			None => return Ok(Value::Nil),
-			Some(v) => if vmcall!(vm; func.clone(), cell_take(v))?.truthy() {
+			Some(v) => if vmcall!(vm; func.clone(), v)?.truthy() {
 				return Ok(i.into())
 			}
 		}
@@ -812,7 +760,6 @@ pub fn find(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 		match vmcalliter!(vm; iter.clone())? {
 			None => return Ok(Value::Nil),
 			Some(v) => {
-				let v = cell_take(v);
 				if vmcall!(vm; func.clone(), v.clone())?.truthy() {
 					return Ok(v)
 				}
@@ -829,7 +776,6 @@ pub fn count(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let mut map = HashMap::new();
 
 	while let Some(v) = vmcalliter!(vm; iter.clone())? {
-		let v = cell_take(v);
 		let hv = v.try_into()?;
 		map.entry(hv)
 			.and_modify(|v: &mut Value| *v = (v.clone() + Value::Int(1)).unwrap())
diff --git a/talc-std/src/num.rs b/talc-std/src/num.rs
index ed6d386..5b1d91e 100644
--- a/talc-std/src/num.rs
+++ b/talc-std/src/num.rs
@@ -1,7 +1,7 @@
 use std::cmp::Ordering;
 
 use lazy_static::lazy_static;
-use talc_lang::{parse_int, symbol::{Symbol, SYM_TYPE_ERROR}, throw, value::{exception::Result, Complex64, Value}, Vm};
+use talc_lang::{parse_int, symbol::{Symbol, SYM_TYPE_ERROR}, throw, value::{Complex64, Value}, Vm, exception::Result};
 use talc_macros::native_func;
 
 use crate::{unpack_args, unpack_varargs};
@@ -142,6 +142,7 @@ fn to_radix_inner(n: i64, radix: u32) -> String {
 	String::from_utf8(result).expect("string was not valid utf8")
 }
 
+
 #[native_func(1)]
 pub fn bin(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let [_, x] = unpack_args!(args);
@@ -233,46 +234,7 @@ fn isqrt_inner(mut n: i64) -> i64 {
 	c
 }
 
-#[native_func(1)]
-pub fn isqrt(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
-	let [_, x] = unpack_args!(args);
-	let Value::Int(x) = x else {
-		throw!(*SYM_TYPE_ERROR, "isqrt expected integer argument, got {x:#}")
-	};
-	if x < 0 {
-		throw!(*SYM_TYPE_ERROR, "isqrt: argument must be positive")
-	}
-	Ok(isqrt_inner(x).into())
-}
-
-#[native_func(1)]
-pub fn isprime(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
-	let [_, x] = unpack_args!(args);
-	let Value::Int(x) = x else {
-		throw!(*SYM_TYPE_ERROR, "isprime expected integer argument, got {x:#}")
-	};
-	if x < 2 {
-		return Ok(false.into())
-	}
-	for p in [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53] {
-		if x % p == 0 {
-			return Ok((x == p).into())
-		}
-	}
-	if x < 59 {
-		return Ok(false.into())
-	}
-	let lim = isqrt_inner(x);
-	let mut i = 54;
-	while i <= lim {
-		if x % (i + 1) == 0 { return Ok(false.into()) }
-		if x % (i + 5) == 0 { return Ok(false.into()) }
-		i += 6;
-	}
-	Ok(true.into())
-}
-
-fn gcd_inner(a: i64, b: i64) -> i64 {
+pub fn gcd_inner(a: i64, b: i64) -> i64 {
 	let (mut a, mut b) = (a.abs(), b.abs());
 	if a == 0 {
 		return b
@@ -300,6 +262,46 @@ fn gcd_inner(a: i64, b: i64) -> i64 {
 
 }
 
+#[native_func(1)]
+pub fn isqrt(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
+	let [_, x] = unpack_args!(args);
+	let Value::Int(x) = x else {
+		throw!(*SYM_TYPE_ERROR, "isqrt expected integer argument, got {x:#}")
+	};
+	if x < 0 {
+		throw!(*SYM_TYPE_ERROR, "isqrt: argument must be positive")
+	}
+	Ok(isqrt_inner(x).into())
+}
+
+
+#[native_func(1)]
+pub fn isprime(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
+	let [_, x] = unpack_args!(args);
+	let Value::Int(x) = x else {
+		throw!(*SYM_TYPE_ERROR, "isprime expected integer argument, got {x:#}")
+	};
+	if x < 2 {
+		return Ok(false.into())
+	}
+	for p in [2, 3, 5, 7] {
+		if x % p == 0 {
+			return Ok((x == p).into())
+		}
+	}
+	if x < 11 {
+		return Ok(false.into())
+	}
+	let lim = isqrt_inner(x);
+	let mut i = 12;
+	while i <= lim+1 {
+		if x % (i - 1) == 0 { return Ok(false.into()) }
+		if x % (i + 1) == 0 { return Ok(false.into()) }
+		i += 6;
+	}
+	Ok(true.into())
+}
+
 #[native_func(2..)]
 pub fn gcd(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let ([_, x, y], rest) = unpack_varargs!(args);
diff --git a/talc-std/src/random.rs b/talc-std/src/random.rs
index c8e1610..3241008 100644
--- a/talc-std/src/random.rs
+++ b/talc-std/src/random.rs
@@ -1,5 +1,5 @@
-use rand::Rng;
-use talc_lang::{symbol::SYM_TYPE_ERROR, throw, value::{cell_take, exception::Result, range::RangeType, Value}, vmcalliter, Vm};
+use rand::{seq::SliceRandom, Rng};
+use talc_lang::{symbol::SYM_TYPE_ERROR, throw, value::{range::RangeType, Value}, vmcalliter, Vm, exception::Result};
 use talc_macros::native_func;
 
 use crate::unpack_args;
@@ -7,6 +7,7 @@ use crate::unpack_args;
 pub fn load(vm: &mut Vm) {
 	vm.set_global_name("rand", rand().into());
 	vm.set_global_name("rand_in", rand_in().into());
+	vm.set_global_name("shuf", shuf().into());
 }
 
 #[native_func(0)]
@@ -19,32 +20,55 @@ pub fn rand_in(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
 	let [_, col] = unpack_args!(args);
 	match col {
 		Value::List(l) => {
-			let l = l.borrow();
-			let i = rand::thread_rng().gen_range(0..l.len());
-			Ok(l[i].clone())
+            let l = l.borrow();
+			let Some(v) =  l.choose(&mut rand::thread_rng()) else {
+                throw!(*SYM_TYPE_ERROR, "rand_in: empty list")
+            };
+            Ok(v.clone())
 		},
 		Value::Table(t) => {
 			let t = t.borrow();
+			if t.is_empty() {
+                throw!(*SYM_TYPE_ERROR, "rand_in: empty table")
+            };
 			let i = rand::thread_rng().gen_range(0..t.len());
 			let key = t.keys().nth(i).unwrap();
 			Ok(key.clone().into_inner())
 		},
-		Value::Range(r) => match r.ty {
-			RangeType::Open => Ok(Value::Int(
-				rand::thread_rng().gen_range(r.start..r.stop))),
-			RangeType::Closed => Ok(Value::Int(
-				rand::thread_rng().gen_range(r.start..=r.stop))),
-			RangeType::Endless => throw!(*SYM_TYPE_ERROR, "cannot select random element of endless range"),
-		},
+		Value::Range(r) => {
+            if r.is_empty() {
+                throw!(*SYM_TYPE_ERROR, "rand_in: empty range")
+            }
+            match r.ty {
+                RangeType::Open => Ok(Value::Int(
+                    rand::thread_rng().gen_range(r.start..r.stop))),
+                RangeType::Closed => Ok(Value::Int(
+                    rand::thread_rng().gen_range(r.start..=r.stop))),
+                RangeType::Endless => throw!(*SYM_TYPE_ERROR, "rand_in: endless range"),
+            }
+        }
 		col => {
 			let iter = col.to_iter_function()?;
 			let mut values = Vec::new();
 			while let Some(v) = vmcalliter!(vm; iter.clone())? {
 				values.push(v);
 			}
+            if values.len() == 0 {
+                throw!(*SYM_TYPE_ERROR, "rand_in: empty iterator")
+            }
 			let i = rand::thread_rng().gen_range(0..values.len());
 			let v = values.swap_remove(i);
-			Ok(cell_take(v))
+			Ok(v)
 		}
 	}
 }
+
+#[native_func(1)]
+pub fn shuf(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
+	let [_, list] = unpack_args!(args);
+    let Value::List(list) = list else {
+        throw!(*SYM_TYPE_ERROR, "shuf expected list, got {list:#}")
+    };
+    list.borrow_mut().shuffle(&mut rand::thread_rng());
+    Ok(Value::List(list))
+}
diff --git a/talc-std/src/value.rs b/talc-std/src/value.rs
index ee5edf9..a192756 100644
--- a/talc-std/src/value.rs
+++ b/talc-std/src/value.rs
@@ -1,6 +1,6 @@
 use std::{cell::RefCell, collections::HashMap, rc::Rc};
 
-use talc_lang::{exception, parse_float, parse_int, symbol::SYM_TYPE_ERROR, throw, value::{exception::Result, HashValue, Value}, Vm};
+use talc_lang::{exception, parse_float, parse_int, symbol::SYM_TYPE_ERROR, throw, value::{HashValue, Rational64, Value}, Vm, exception::Result};
 use talc_macros::native_func;
 
 use crate::unpack_args;
@@ -59,8 +59,15 @@ pub fn as_(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
 		(Value::Int(x), "ratio") => Ok(Value::Ratio(x.into())),
 		(Value::Int(x), "float") => Ok(Value::Float(x as f64)),
 		(Value::Int(x), "complex") => Ok(Value::Complex((x as f64).into())),
+		(Value::Ratio(x), "int") => Ok(Value::Int(*x.numer() / *x.denom())),
 		(Value::Ratio(x), "float") => Ok(Value::Float(*x.numer() as f64 / *x.denom() as f64)),
 		(Value::Ratio(x), "complex") => Ok(Value::Complex((*x.numer() as f64 / *x.denom() as f64).into())),
+		(Value::Float(x), "int") => Ok(Value::Int(x as i64)),
+		(Value::Float(x), "ratio") => {
+            let r = Rational64::approximate_float(x)
+                .ok_or_else(|| exception!(*SYM_TYPE_ERROR, "float {x:?} could not be converted to ratio"))?;
+            Ok(Value::Ratio(r))
+        }
 		(Value::Float(x), "complex") => Ok(Value::Complex(x.into())),
 
 		(Value::String(s), "int")
@@ -85,18 +92,19 @@ pub fn copy_inner(value: Value) -> Result<Value> {
 			| Value::Complex(_) | Value::Range(_) | Value::String(_)
 			=> Ok(value),
 		Value::Cell(c) => {
-			let c = copy_inner(talc_lang::value::cell_take(c))?;
+            let c = Rc::unwrap_or_clone(c).take();
+			let c = copy_inner(c)?;
 			Ok(RefCell::new(c).into())
 		},
 		Value::List(l) => {
-			let l = talc_lang::value::cell_take(l);
+            let l = Rc::unwrap_or_clone(l).take();
 			let v: Result<Vec<Value>> = l.into_iter()
 				.map(copy_inner)
 				.collect();
 			Ok(v?.into())
 		},
 		Value::Table(t) => {
-			let t = talc_lang::value::cell_take(t);
+            let t = Rc::unwrap_or_clone(t).take();
 			let v: Result<HashMap<HashValue, Value>> = t.into_iter()
 				.map(|(k, v)| copy_inner(v).map(|v| (k, v)))
 				.collect();