diff --git a/luminapath/std/list/lib.lm b/luminapath/std/list/lib.lm
index 2b46b1b..429079e 100644
--- a/luminapath/std/list/lib.lm
+++ b/luminapath/std/list/lib.lm
@@ -2,6 +2,7 @@ use std:maybe [Maybe [..]]
 use std:math [Compare, Num [+]]
 use vec [Vec]
 use slice [Slice]
+use ring [Deque]
 use std:io [crash]
 
 @![langItem(list as List)]
@@ -49,10 +50,22 @@ pub fn ++ left right as List a, List a -> [a] =
     | _ -> Concat left right
 
 // TODO: we should remake this in a vastly more performant way by taking advantage of the concrete variants
-pub fn fold f acc list as fn(b, a -> b), b, [a] -> b =
+pub fn fold f acc list as fn(b, a -> b), b, List a -> b =
   match list
-  | [x : xs] -> fold #f (f acc x) xs
-  | []       -> acc
+  | Slice slice -> slice:fold #f acc slice
+  | Concat left right -> fold #f (fold #f acc left) right
+  | Singleton v -> f acc v
+  | Nil -> acc
+  // match list
+  // | [x : xs] -> fold #f (f acc x) xs
+  // | []       -> acc
+
+// Fold over a counter
+pub fn ifold f acc n as fn(b, uint -> b), b, uint -> b = 
+  next 0 acc
+ where
+  fn next i acc as uint, b -> b = 
+    if n == i then acc else next (i + 1) (f acc i)
 
 // TODO: we should remake this in a vastly more performant way by taking advantage of the concrete variants
 pub fn map f list as fn(a -> b), [a] -> [b] =
@@ -61,9 +74,26 @@ pub fn map f list as fn(a -> b), [a] -> [b] =
   | []       -> []
 
 pub fn flat_map f list as fn(a -> [b]), [a] -> [b] = 
+  fold #(\acc x -> acc ++ f x) [] list
+
+when a can Compare
+pub fn trim v list as a, [a] -> [a] = 
   match list
-  | [x : xs] -> f x ++ flat_map #f xs
-  | []       -> []
+  | [x : xs] -> 
+    if x == v
+      then trim_right v xs
+      else trim_right v (x : xs)
+  | [] -> []
+
+when a can Compare
+pub fn trim_right v list as a, [a] -> [a] = 
+  match list
+  | [x] -> 
+    if x == v 
+      then []
+      else [x]
+  | [x : xs] -> x : trim_right v xs
+  | [] -> []
 
 // TODO: we should split out equality operator from Compare, then we can use a constraint here instead
 pub fn deduplicate f list as fn(a, a -> bool), [a] -> [a] = 
diff --git a/luminapath/std/list/slice.lm b/luminapath/std/list/slice.lm
index 37f9fb3..8f7dd02 100644
--- a/luminapath/std/list/slice.lm
+++ b/luminapath/std/list/slice.lm
@@ -1,4 +1,5 @@
 use std:list:vec [unsafe_take, from_range]
+use std:list [ifold]
 
 pub type Slice a {
   // For pointer marking to work in the GC we need to hold on to the root
@@ -32,6 +33,9 @@ pub fn unsafe_get i slice as uint, Slice a -> a =
 
 pub fn len {len} as Slice a -> uint = len
 
+pub fn fold f acc slice as fn(b, a -> b), b, Slice a -> b =
+  ifold #(\acc i -> f acc (unsafe_get i slice)) acc slice.len
+
 pub fn forEach f slice as fn(a -> ()), Slice a -> () =
   list:itimes #visit slice.len
  where
diff --git a/luminapath/std/list/vec.lm b/luminapath/std/list/vec.lm
index 7d15092..db36acb 100644
--- a/luminapath/std/list/vec.lm
+++ b/luminapath/std/list/vec.lm
@@ -60,6 +60,11 @@ pub fn map f vec as fn(a -> b), Vec a -> Vec b =
     (0, vec.len)
     #(\i -> unsafe_get i vec . f)
 
+pub fn clone vec as Vec a -> Vec a =
+  from_range
+    (0, vec.len)
+    #(\i -> unsafe_get i vec)
+
 when a can ToString
 impl ToString for Vec a
   fn show vec as self -> string =
diff --git a/luminapath/std/ptr/lib.lm b/luminapath/std/ptr/lib.lm
index e3110a7..622df7f 100644
--- a/luminapath/std/ptr/lib.lm
+++ b/luminapath/std/ptr/lib.lm
@@ -24,3 +24,6 @@ when t can Type
 pub fn box v as t -> *t =
   let ptr = alloc(t as t) in
     do write ptr v then ptr
+
+pub fn memcpy to from count as *a, *a, uint -> () =
+  builtin:memcpy to from (Type(a):size * count)
diff --git a/luminapath/std/string/lib.lm b/luminapath/std/string/lib.lm
index 98422a7..0d09b15 100644
--- a/luminapath/std/string/lib.lm
+++ b/luminapath/std/string/lib.lm
@@ -57,6 +57,9 @@ pub type string {
   inner List u8
 }
 
+pub fn trim v list as u8, string -> string = 
+  { string | inner = list.inner . trim v }
+
 pub fn len {inner} as string -> uint = inner . len
 
 pub fn take n str as uint, string -> string =