From c36d7ffc7c771fcece05bf882fee02fae4261edf Mon Sep 17 00:00:00 2001
From: Konstantin Molchanov <moigagoo@live.com>
Date: Wed, 27 Dec 2017 13:30:32 +0400
Subject: [PATCH 1/3] Tables: make `toCountTable` actually count the elements
 of the input openArray.

---
 lib/pure/collections/tables.nim | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/pure/collections/tables.nim b/lib/pure/collections/tables.nim
index 01767956ea..d8c133bce3 100644
--- a/lib/pure/collections/tables.nim
+++ b/lib/pure/collections/tables.nim
@@ -968,7 +968,7 @@ proc initCountTable*[A](initialSize=64): CountTable[A] =
 proc toCountTable*[A](keys: openArray[A]): CountTable[A] =
   ## creates a new count table with every key in `keys` having a count of 1.
   result = initCountTable[A](rightSize(keys.len))
-  for key in items(keys): result[key] = 1
+  for key in items(keys): result.inc key
 
 proc `$`*[A](t: CountTable[A]): string =
   ## The `$` operator for count tables.

From b592f069bbc2d30f11fd9414e149025653425dc0 Mon Sep 17 00:00:00 2001
From: Konstantin Molchanov <moigagoo@live.com>
Date: Wed, 27 Dec 2017 13:44:47 +0400
Subject: [PATCH 2/3] Tables: toCountTable: Update docs.

---
 lib/pure/collections/tables.nim | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/pure/collections/tables.nim b/lib/pure/collections/tables.nim
index d8c133bce3..777beabc39 100644
--- a/lib/pure/collections/tables.nim
+++ b/lib/pure/collections/tables.nim
@@ -966,7 +966,8 @@ proc initCountTable*[A](initialSize=64): CountTable[A] =
   newSeq(result.data, initialSize)
 
 proc toCountTable*[A](keys: openArray[A]): CountTable[A] =
-  ## creates a new count table with every key in `keys` having a count of 1.
+  ## creates a new count table with every key in `keys` having a count
+  ## of how many times it occurs in `keys`.
   result = initCountTable[A](rightSize(keys.len))
   for key in items(keys): result.inc key
 

From a8b0a8a92da03593c3fe52dfbca8ee4eeed286d3 Mon Sep 17 00:00:00 2001
From: Konstantin Molchanov <moigagoo@live.com>
Date: Wed, 27 Dec 2017 17:29:39 +0400
Subject: [PATCH 3/3] Changelog: Document `toCountTable` behaviour change.

---
 changelog.md | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/changelog.md b/changelog.md
index 5734a4cb12..de4b2f251b 100644
--- a/changelog.md
+++ b/changelog.md
@@ -146,7 +146,7 @@ This now needs to be written as:
 - Asynchronous programming for the JavaScript backend using the `asyncjs` module.
 - Extra semantic checks for procs with noreturn pragma: return type is not allowed,
   statements after call to noreturn procs are no longer allowed.
-- Noreturn proc calls and raising exceptions branches are now skipped during common type 
+- Noreturn proc calls and raising exceptions branches are now skipped during common type
   deduction in if and case expressions. The following code snippets now compile:
 ```nim
 import strutils
@@ -159,10 +159,29 @@ let b = case str:
   of nil, "": raise newException(ValueError, "Invalid boolean")
   elif str.startsWith("Y"): true
   elif str.startsWith("N"): false
-  else: false 
-let c = if str == "Y": true 
-  elif str == "N": false 
+  else: false
+let c = if str == "Y": true
+  elif str == "N": false
   else:
-    echo "invalid bool" 
+    echo "invalid bool"
     quit("this is the end")
 ```
+- Proc [toCountTable](https://nim-lang.org/docs/tables.html#toCountTable,openArray[A]) now produces a `CountTable` with values correspoding to the number of occurrences of the key in the input. It used to produce a table with all values set to `1`.
+
+Counting occurrences in a sequence used to be:
+
+```nim
+let mySeq = @[1, 2, 1, 3, 1, 4]
+var myCounter = initCountTable[int]()
+
+for item in mySeq:
+  myCounter.inc item
+```
+
+Now, you can simply do:
+
+```nim
+let
+  mySeq = @[1, 2, 1, 3, 1, 4]
+  myCounter = mySeq.toCountTable()
+```