2 files changed, 19 insertions, 2 deletions
diff --git a/lib/pure/collections/lists.nim b/lib/pure/collections/lists.nim
index 0b3708a7c..15ce5d074 100644
--- a/lib/pure/collections/lists.nim
+++ b/lib/pure/collections/lists.nim
@@ -140,11 +140,26 @@ proc contains*[T](L: SomeLinkedCollection[T], value: T): bool {.inline.} =
   ## exist, true otherwise.
   result = find(L, value) != nil
 
+proc append*[T](L: var SinglyLinkedList[T],
+                n: SinglyLinkedNode[T]) {.inline.} =
+  ## appends a node `n` to `L`. Efficiency: O(1).
+  n.next = nil
+  if L.tail != nil:
+    assert(L.tail.next == nil)
+    L.tail.next = n
+  L.tail = n
+  if L.head == nil: L.head = n
+
+proc append*[T](L: var SinglyLinkedList[T], value: T) {.inline.} =
+  ## appends a value to `L`. Efficiency: O(1).
+  append(L, newSinglyLinkedNode(value))
+
 proc prepend*[T](L: var SinglyLinkedList[T],
                  n: SinglyLinkedNode[T]) {.inline.} =
   ## prepends a node to `L`. Efficiency: O(1).
   n.next = L.head
   L.head = n
+  if L.tail == nil: L.tail = n
 
 proc prepend*[T](L: var SinglyLinkedList[T], value: T) {.inline.} =
   ## prepends a node to `L`. Efficiency: O(1).
diff --git a/lib/pure/collections/sharedstrings.nim b/lib/pure/collections/sharedstrings.nim
index 7e9de4b73..b283cd4b1 100644
--- a/lib/pure/collections/sharedstrings.nim
+++ b/lib/pure/collections/sharedstrings.nim
@@ -12,6 +12,8 @@
 type
   UncheckedCharArray = UncheckedArray[char]
 
+import system/helpers2
+
 type
   Buffer = ptr object
     refcount: int
@@ -49,11 +51,11 @@ proc len*(s: SharedString): int = s.len
 
 proc `[]`*(s: SharedString; i: Natural): char =
   if i < s.len: result = s.buffer.data[i+s.first]
-  else: raise newException(IndexError, "index out of bounds")
+  else: raise newException(IndexError, formatErrorIndexBound(i, s.len-1))
 
 proc `[]=`*(s: var SharedString; i: Natural; value: char) =
   if i < s.len: s.buffer.data[i+s.first] = value
-  else: raise newException(IndexError, "index out of bounds")
+  else: raise newException(IndexError, formatErrorIndexBound(i, s.len-1))
 
 proc `[]`*(s: SharedString; ab: HSlice[int, int]): SharedString =
   #incRef(src.buffer)