proposal/custom-type-errors.md

@@ -322,4 +322,10 @@ testNotOk :: Struct MyOtherStruct -> Ptr Word8
 testNotOk s = get s (Proxy :: Proxy "B")
 --}
 
-```
\ No newline at end of file
+```
+
+## See also
+
+
+The Helium people have also addressed the problem of customizable error messages.
+See Heeren, Hage, Swierstra on [ Scripting the Type Inference Process](http://www.staff.science.uu.nl/~hage0101/scriptingthetypeinferencer.pdf).