[Haskell-cafe] Showing the 1 element tuple

[John Meacham]

On Fri, Dec 22, 2006 at 11:13:50AM -0800, Dan Weston wrote:
> More generally, is there an operator version of dotted pair notation 
> (gasp, did I just lisp?) that works like:
> 
> data Tuple a b = () | Tuple a b
> 
> ()    == ()
> ( ) 1 == Tuple 1 ()
> (2,'a',"hello") == Tuple 2 (Tuple 'a' (Tuple "hello" ()))
> 
> And is there anyway in Haskell to restrict the type definition above to 
> require that b be a type that can be constructed (possibly recursively) 
> with only () or Tuple, so the user doesn't do something stupid like 
> Tuple 1 'a', which is not a valid dotted pair?

HList seems similar to what you are going for:

http://homepages.cwi.nl/~ralf/HList/

        John

-- 
John Meacham - ⑆repetae.net⑆john⑈