Update 'ideas.md'

ideas.md

@@ -33,7 +33,7 @@ Good GUI solutions are important. Haskell still has no reasonable GUI solutions,
   - Things like piping etc. possible with type-safety
   - How to most elegantly integrate non-Katrin programs?
 
-### Data-centric
+### Data handling
 
 In the real-world, working with external data in file systems and databases is one of the most important tasks for programs. It should be easy.
 
@@ -42,6 +42,12 @@ In the real-world, working with external data in file systems and databases is o
 - ~~*Languages* (regular, context-free) at the language heart~~
   - *Probably* nonsense
 
+### Interfacing
+
+What to do with typeclasses? Are they good, are they bad?
+
+Don't concentrate on actual types and data, but rather on "capabilities"? <http://degoes.net/articles/kill-data>
+
 ### Proofing
 
 - Possible, but no priority