[Hs-Generics] A Lightweight Implementation of Generics and Dynamics (LIGD)

[Stefan Holdermans]

Stephanie,

> What do you mean by "local redefinitions"?

I suppose it could be described as "scoped specializability"; see  
Chapter 8 of Andres' thesis [1].

Examples of local redefinitions in GH:

   -- case-insenstive equality
   let equals {| a |} c1 c2 = equals {| Char |} (toUpper c1) (toUpper  
c2)
   in  equals {| [a] |} "Hello" "hEllo"

   -- length of the list
   let size {| a |} x = 1
   in  size {| [a] |} [2, 3, 5, 7]

   -- map toUpper
   let map {| a |} = toUpper
   in  map {| [a] |} "Hello, world!"

   -- flattens the list of lists
   let collect {| a |} x = [x]
   in  collect {| [[a]] |} xss

   -- unlines
   let collect {| a |} s = s ++ "\n"
   in  collect {| [a] |} ["Hello", "World"]

Cheers,

   Stefan

----
[1] Andres Loeh. Exploring Generic Haskell. Ph.D. thesis, Utrecht  
University, 2004.