Hi@all! I'd like to hear some comments about the following ideas; maybe they are someway obsolete or even useless nonsense. A few days ago, I thought about abstracting the instance of an object away, like used in Foreign.Storable.sizeOf::(Storable a)=>a->Int, where only the type of an object is used. The problem with the function sizeOf is, that the result should be constant per definition(*), but how can we make the compiler know this? (*) http://www.haskell.org/ghc/docs/latest/html/libraries/base/Foreign-Storable....
sizeOf::a->Int "Computes the storage requirements (in bytes) of the argument. The value of the argument is not used."
So I thought we may need a new (abstract) datatype to wrap the type of an object, just to contain no dynamic data: data Type a typeOf :: a -> Type a typeOf = undefined #define TYPE(a) (undefined::Type (a)) ... sizeOf :: (Storable a) => Type a -> Int Maybe this is a little bit too ugly and cumbersomely, just to make sizeOf constant. This version of sizeOf is not really comfortable anymore; but it isn't comfortable to write "(undefined::a)", too. To be able to write "(::a)" instead, would be really nice, IMHO; but how about "(_::a)"? ---------- <trying to be equivocating> undefined is another way to implement ...nothing. More comfortable would it be to write a single symbol instead of the long word "undefined": _ :: a _ = undefined Using "_" as a function should not be such a problem: it cannot be mixed with the joker "_" as parameter. To define this function may be a problem: It needs a compiler-patch to allow this, ATM. ---------- By the way, this symbol is not used at type-level... How about praefix/postfix operators instead of only infix? -- praefix newtype BigLambda a = BigLambda a (/\) :: _ -> a -> BigLambda a /\ a = BigLambda a -- postfix newtype Lifted a = Lifted a (!^) :: a -> _ -> Lifted a a !^ = Lifted a May this be confusing? Or even impossible? Am I insane? Well, I don't know how hard it would be to implement those language features. I would not like to make anyone implement all this, if it is only a niceToHave-butIDontUseIt, like the implicit parameters feature. - marc