standard-classes.md

@@ -4,20 +4,9 @@
 This page collects issues and proposals for the standard classes.
 Many of the proposals involve additional superclasses, which would be less burdensome with [class aliases](https://gitlab.haskell.org//haskell/prime/issues/101) or something similar, but such features are not yet implemented.
 
-## The Read class
+## Constructor classes
 
-
-See [ReadClass](read-class).
-
-## The Enum class
-
-
-Issues:
-
-- `succ` and `pred` are unused.
-- The default definitions of `enum`\* would make more sense if `toEnum` and `fromEnum` used `Integer` instead of `Int`.
-
-## The Functor class
+### The Functor class
 
 
 Proposal:
@@ -66,7 +55,8 @@ Issues:
 
 Proposals:
 
-- a group-like class with `zero`, `(+)` and `negate`/`(-)`.
+- a group-like class with `zero`, `(+)` and `negate`/`(-)`
+  (could be further split with a monoid sub-class)
 - a ring-like subclass adding `(*)` and `one`/`fromInteger`, with the existing `Num` class as a further subclass.
 
 
@@ -77,8 +67,9 @@ Note that the `Float` and `Double` instances will not satisfy the usual axioms f
 
 Issues:
 
-- `div` and `mod` also sense for rationals and polynomials, but `Ord`, `Num` and `toInteger` (and `toRational` for polynomials) don't.
-  However `quot` and `rem` assume an ordering.
+- `div` and `mod` also sense for rationals and polynomials, but `toInteger` does not.
+  `Ord`, `Num(abs, signum)`, `toInteger` and `toRational` don't make sense for polynomials.
+  `quot` and `rem` assume an ordering.
 
 ### The Fractional class
 
@@ -99,7 +90,22 @@ Proposals:
 
   This is independent of all the other proposals.
 
-## The Ix class
+## Other standard classes
+
+### The Read class
+
+
+See [ReadClass](read-class).
+
+### The Enum class
+
+
+Issues:
+
+- `succ` and `pred` are unused.
+- The default definitions of `enum`\* would make more sense if `toEnum` and `fromEnum` used `Integer` instead of `Int`.
+
+### The Ix class
 
 
 Issues: