On Wed, 24 Jan 2007, Claus Reinke wrote:
the alternative I'm aiming for, as exhibited in the consP example, would be to build patterns systematically from view patterns used as abstract de-constructors, composed in the same way as one would compose the abstract constructors to build the abstract data structure. in other words, you define your pattern constructors once, with the adt, and export them; and anytime you want to match somethind of that abstract type, you simply compose your pattern from those abstract pattern constructors.
This would cause an awful lot of kludging to get around the fact you need to declare a new ADT to declare new abstract deconstructors, and requires an additional extension for abstract deconstructors to be typeclass methods - something abstract constructors can do for free. Neither seems gainful to me. -- flippa@flippac.org Performance anxiety leads to premature optimisation