diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,7 @@
 # mixed-types-num change log
 
+* v 0.5.8 2021-06-02
+  * add HasRationals to Field
 * v 0.5.7 2021-05-28
   * before: n^m is rational, now: n^m is integer, n^^m is rational
 * v 0.5.6 2021-05-27
diff --git a/mixed-types-num.cabal b/mixed-types-num.cabal
--- a/mixed-types-num.cabal
+++ b/mixed-types-num.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: b38cac48ab06aac0296ad4583bea2ac45261122fa0b952f259489586adfe528a
+-- hash: 577d524d309a29822adf0ad8117bd81096101b172ce94f23e11273dba5235297
 
 name:           mixed-types-num
-version:        0.5.7.0
+version:        0.5.8.0
 synopsis:       Alternative Prelude with numeric and logic expressions typed bottom-up
 description:    Please see the README on GitHub at <https://github.com/michalkonecny/mixed-types-num#readme>
 category:       Math
diff --git a/src/Numeric/MixedTypes/Field.hs b/src/Numeric/MixedTypes/Field.hs
--- a/src/Numeric/MixedTypes/Field.hs
+++ b/src/Numeric/MixedTypes/Field.hs
@@ -26,7 +26,7 @@
 import Numeric.CollectErrors ( CN )
 -- import qualified Numeric.CollectErrors as CN
 
--- import Numeric.MixedTypes.Literals
+import Numeric.MixedTypes.Literals
 -- import Numeric.MixedTypes.Bool
 -- import Numeric.MixedTypes.Eq
 import Numeric.MixedTypes.Ord
@@ -43,6 +43,7 @@
 
 class
   (Ring t,
+   HasRationals t,
    CanPowBy t Integer, CanPowBy t Int,
    CanDivSameType t, CanRecipSameType t,
    CanAddSubMulDivBy t Rational,