Changes between Version 11 and Version 12 of Records/OverloadedRecordFields

Timestamp:

01/15/12 12:05:12 (17 months ago)

Author:

strake888

Comment:

--

Records/OverloadedRecordFields

@@ -358 +358 @@
  * Not overloaded, so you can't abstract over it.
 
+== Alternative Proposal ==
+
+{{{
+class Has r k v where select :: r -> k -> v;
+class Quasifunctor r s k u v where qfmap :: k -> (u -> v) -> r -> s;
+}}}
+
+Then, for example:
+{{{
+data R a = R { x :: a };
+
+-- automatically-generated instances
+instance Has (R a) "x" a where ...
+instance Quasifunctor (R a) (R b) "x" a b where ...
+
+r = R { x = 256 };
+-- assign value 3 to r.x
+let s = qfmap (undefined :: "x") (const 3) r in ...
+}}}
 
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