[Haskell-cafe] Re: Renaming constructors for readability

Dougal Stanton wrote:

I wonder, is there an equivalent of the 'type' keyword for constructors? An example:

-- create a pseudo-C pointer type -- which can point to a value or a -- null. type Pointer a = Maybe a

-- int a = 3; -- int *pa = &a; ampersand :: t -> Pointer t ampersand a = Just a

-- int b = *pa. star :: Pointer a -> a star (Just a) = a -- note this function behaves -- in an 'authentic' fashion ;-)

To really complete the illusion it would be nice to replace the names Just and Nothing with PointerTo and Null. Then the constructors would really mean something. Is there a solution?

The thing you want is called "views". See http://hackage.haskell.org/trac/ghc/wiki/ViewPatterns#Relatedwork for more. Regards, apfelmus