diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,6 @@
-* v 0.3.1 2017-08-15
+* v 0.3.1.1 2017-08-15
   * provided compatible versions of take, drop, length, replicate, splitAt
+  * added missing mixed-type subtraction combination to Ring etc.
 
 * v 0.3.0.1 2017-08-01
   * improve package documentation in module MixedTypesNumPrelude
diff --git a/mixed-types-num.cabal b/mixed-types-num.cabal
--- a/mixed-types-num.cabal
+++ b/mixed-types-num.cabal
@@ -1,5 +1,5 @@
 name:           mixed-types-num
-version:        0.3.1
+version:        0.3.1.1
 cabal-version:  >= 1.9.2
 build-type:     Simple
 homepage:       https://github.com/michalkonecny/mixed-types-num
diff --git a/src/MixedTypesNumPrelude.hs b/src/MixedTypesNumPrelude.hs
--- a/src/MixedTypesNumPrelude.hs
+++ b/src/MixedTypesNumPrelude.hs
@@ -95,14 +95,14 @@
 
 === Dividing integers, dealing with potential error
 
->>> :t let n = 1 :: Integer in n/(n+1)
+>>> :t let n = 1 in n/(n+1)
 ... :: CollectErrors [(ErrorCertaintyLevel, NumError)] Rational
 
 A shorter synonym of this type is @CN Rational@.
 We use the shorter form below for better readability of this documentation
 although ghci usually prints the longer version:
 
->>> :t let n = 1 :: Integer in n/(n+1)
+>>> :t let n = 1 in n/(n+1)
 ... :: CN Rational
 
 The @CN@ wrapper here indicates that integer division can fail for some values:
@@ -230,17 +230,6 @@
     * Not all Prelude numerical types are supported yet.
       Eg @Natural@ and @Float@ are not supported at present,
       but @Double@ is supported.
-
-    * Prelude operations such as @length@, @take@ are exported unchanged,
-      which sometimes requires one to write extra conversions such as:
-
-      > take (int 5) list
-      > (integer (length list))
-
-      It is planned to shadow these functions with more flexible equivalents.
-      The operator @!!@ is already shadowed by a more flexible version,
-      allowing the index to be of type @Integer@ as well as @Int@.
-
 
     * Inferred types can be very large. Eg for @f a b c = sqrt (a + b * c + 1)@ the inferred type is: