ross:
On Thu, Sep 14, 2006 at 07:51:59PM +0200, Bertram Felgenhauer wrote:
It's a result of thinking about lazy evaluation, and especially lazy patterns (and let bindings) for some time. A wiki article that helped me a lot to understand these is
http://www.haskell.org/hawiki/TyingTheKnot
I'd like to point out the trustList function there which uses the idea of encoding the structure of a term and its actual values in different arguments, i.e. a blueprint.
One view of your device is as separating the shape (blueprint) from the contents, e.g. one can split a finite map type
data Map k a = Node !Int k a (Map k a) (Map k a) | Leaf
into a pair of types
data MapShape k = SNode !Int k (MapShape k) (MapShape k) | SLeaf data MapData a = DNode a (MapData a) (MapData a) | DLeaf
... Nice description. Ross, I added a wiki page for this technique. Would you like to either elaborate on the wiki, or include the text of your email to it? http://haskell.org/haskellwiki/Separating_shape_and_content Cheers, Don