monoid-extras 0.1.1.0 → 0.2.0.0

raw patch · 3 files changed

+17/−9 lines, 3 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• CHANGES +6/−0
• monoid-extras.cabal +1/−1
• src/Data/Monoid/Action.hs +10/−8

@@ -1,3 +1,9 @@+* 0.2.0.0++  - Remove instances for actions on pairs and triples, and add some+    commentary explaining why adding them was a bad idea in the first+    place.+ * 0.1.1.0    - Add instances for actions on pairs and triples

@@ -1,5 +1,5 @@ name:                monoid-extras-version:             0.1.1.0+version:             0.2.0.0 synopsis:            Various extra monoid-related definitions and utilities description:         Various extra monoid-related definitions and utilities,                      such as monoid actions, monoid coproducts, "deletable"

@@ -44,6 +44,16 @@ --   > instance Action M s -- --   with no method implementations.+--+--   It is a bit awkward dealing with instances of @Action@, since it+--   is a multi-parameter type class but we can't add any functional+--   dependencies---the relationship between monoids and the types on+--   which they act is truly many-to-many.  In practice, this library+--   has chosen to have instance selection for @Action@ driven by the+--   /first/ type parameter.  That is, you should never write an+--   instance of the form @Action m SomeType@ since it will overlap+--   with instances of the form @Action SomeMonoid t@.  Newtype+--   wrappers can be used to (awkwardly) get around this. class Action m s where    -- | Convert a value of type @m@ to an action on @s@ values.@@ -54,11 +64,3 @@ instance Action m s => Action (Option m) s where   act (Option Nothing)  s = s   act (Option (Just m)) s = act m s---- | Actions operate elementwise on pairs.-instance (Action m a, Action m b) => Action m (a,b) where-  act m (a,b) = (act m a, act m b)---- | Actions operate elementwise on triples.-instance (Action m a, Action m b, Action m c) => Action m (a,b,c) where-  act m (a,b,c) = (act m a, act m b, act m c)