fixup! Turn Coercible into a symmetric and transitive relation

Author: kl0tl

src/Language/PureScript/Docs/Prim.hs

@@ -380,13 +380,17 @@ coercible = primClassOf (P.primSubName "Coerce") "Coercible" $ T.unlines
   , "This class does not have regular instances; instead they are created"
   , "on-the-fly during type-checking according to a set of rules."
   , ""
-  , "First, Coercible obeys reflexivity, any type has the same representation"
-  , "as itself and symmetry, pairs of types can be coerced both ways:"
+  , "First, Coercible obeys reflexivity - any type has the same representation"
+  , "as itself:"
   , ""
   , "    instance coercibleReflexive :: Coercible a a"
+  , ""
+  , "Second, Coercible obeys symmetry - if a type `a` can be coerced to some"
+  , "other type `b`, then `b` can also be coerced back to `a`:
+  , ""
   , "    instance coercibleSymmetric :: Coercible a b => Coercible b a"
   , ""
-  , "Second, for every type constructor there is an instance that allows one"
+  , "Third, for every type constructor there is an instance that allows one"
   , "to coerce under the type constructor (`data` or `newtype`). For example,"
   , "given a definition:"
   , ""
@@ -402,7 +406,7 @@ coercible = primClassOf (P.primSubName "Coerce") "Coercible" $ T.unlines
   , "such as `b` is thus typically referred to as a \"phantom\" type), `b` and `b'`"
   , "can differ arbitrarily."
   , ""
-  , "Third, for every `newtype NT = MkNT T`, there is a pair of instances which"
+  , "Fourth, for every `newtype NT = MkNT T`, there is a pair of instances which"
   , "permit coercion in and out of the `newtype`:"
   , ""
   , "    instance coercibleNewtypeLeft  :: Coercible a T => Coercible a NT"
@@ -411,7 +415,7 @@ coercible = primClassOf (P.primSubName "Coerce") "Coercible" $ T.unlines
   , "To prevent breaking abstractions, these instances are only usable if the"
   , "constructor `MkNT` is exported."
   , ""
-  , "Fourth, every pair of unsaturated type constructors can be coerced if"
+  , "Fifth, every pair of unsaturated type constructors can be coerced if"
   , "there is an instance for the fully saturated types. For example,"
   , "given the definitions:"
   , ""