From 977bcd23f6a174d872e2faa42e266a78cca5e4e7 Mon Sep 17 00:00:00 2001
From: gcanti <giulio.canti@gmail.com>
Date: Thu, 14 May 2020 18:17:21 +0200
Subject: [PATCH] version 2.6.1

---
 CHANGELOG.md                    | 13 ++++++++++++-
 docs/guides/code-conventions.md | 23 ++++++++++++++++++++++-
 package.json                    |  2 +-
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5ccc54478..d3f3ebbba 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,7 +14,7 @@
 **Note**: Gaps between patch versions are faulty/broken releases. **Note**: A feature tagged as Experimental is in a
 high state of flux, you're at risk of it changing without notice.
 
-# 2.6.0
+# 2.6.1
 
 - **New Feature**
   - add W variants, closes #904 (@gcanti)
@@ -30,6 +30,7 @@ high state of flux, you're at risk of it changing without notice.
   - `IOEither`
     - add `getOrElseW` (@gcanti)
     - add `chainW` (@gcanti)
+    - add `chainEitherKW` (@giogonzo)
   - `Option`
     - add `getOrElseW` (@gcanti)
   - `Reader`
@@ -37,14 +38,24 @@ high state of flux, you're at risk of it changing without notice.
   - `ReaderEither`
     - add `getOrElseW` (@gcanti)
     - add `chainW` (@gcanti)
+    - add `chainEitherKW` (@giogonzo)
   - `ReaderTaskEither`
     - add `getOrElseW` (@gcanti)
     - add `chainW` (@gcanti)
+    - add `chainEitherKW` (@giogonzo)
+    - add `chainTaskEitherKW` (@giogonzo)
+    - add `chainIOEitherKW` (@giogonzo)
   - `StateReaderTaskEither`
     - add `chainW` (@gcanti)
+    - add `chainEitherKW` (@giogonzo)
+    - add `chainTaskEitherKW` (@giogonzo)
+    - add `chainReaderTaskEitherKW` (@giogonzo)
+    - add `chainIOEitherKW` (@giogonzo)
   - `TaskEither`
     - add `getOrElseW` (@gcanti)
     - add `chainW` (@gcanti)
+    - add `chainEitherKW` (@giogonzo)
+    - add `chainIOEitherKW` (@giogonzo)
   - `Tree`
     - add `fold` function (@gcanti)
 
diff --git a/docs/guides/code-conventions.md b/docs/guides/code-conventions.md
index 1d8362554..821521c69 100644
--- a/docs/guides/code-conventions.md
+++ b/docs/guides/code-conventions.md
@@ -92,7 +92,7 @@ in `sequenceT` means *T*uple, I borrowed the name from the corresponding [Haskel
 
 However usually it means *T*ransformer like in "monad transformers" (e.g. `OptionT`, `EitherT`, `ReaderT`, `StateT`)
 
-### What a `K` suffix means, e.g. `fromEitherK` vs `chainEitherK`
+### What a `K` suffix means, e.g. `fromEitherK` or `chainEitherK`
 
 `K` means *K*leisli. A _Kleisli arrow_ is a function with the following signature
 
@@ -147,3 +147,24 @@ pipe(input, IE.chain(IE.fromEitherK(parse)))() // left(new Error('cannot decode
 // or with less boilerplate
 pipe(input, IE.chainEitherK(parse))() // left(new Error('cannot decode "foo" to number'))
 ```
+
+### What a `W` suffix means, e.g. `chainW` or `chainEitherKW`
+
+`W` means *W*iden. Functions that end with `W` are able to aggregate errors into a union (for `Either` based data types) or environments into an intersection (for `Reader` based data types).
+
+**Example**
+
+```ts
+import * as E from 'fp-ts/lib/Either'
+import * as TE from 'fp-ts/lib/TaskEither'
+import { pipe } from 'fp-ts/lib/pipeable'
+
+declare function parseString(s: string): E.Either<string, number>
+declare function fetchUser(id: number): TE.TaskEither<Error, User>
+
+// this raises an error because: Type 'string' is not assignable to type 'Error'
+const program_ = (s: string) => pipe(s, TE.fromEitherK(parseString), TE.chain(fetchUser))
+
+// const program: (s: string) => TE.TaskEither<string | Error, User>
+const program = (s: string) => pipe(s, TE.fromEitherK(parseString), TE.chainW(fetchUser))
+```
diff --git a/package.json b/package.json
index 466355315..ae04f4700 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "fp-ts",
-  "version": "2.6.0",
+  "version": "2.6.1",
   "description": "Functional programming in TypeScript",
   "files": [
     "lib",