jamin1001 wrote:
What if I want to do something like
data Chair = Chair {pos:: Int, color :: Int} data Table = Table {pos:: Int, color :: Int}
data Properties = Props { pos, color :: Int } data Chair = Chair Props data Table = Table Props or: data Chair = Chair Int Int data Table = Table Int Int class Furniture a where pos :: a -> Int color :: a -> Int instance Furniture Chair where pos (Chair x _) = x color (Chair _ c) = c instance Furniture Table where ...
Also, could someone tell me why this doesn't compile in GHC:
data Test = A {a::Int} | B {a::Int, b::Int} data Test2 = C {c::A}
(Test2 line): Not in scope: type constructor or class 'A'
A is a data constructor, and not a type. Try: data Test2 = C { c :: Test }
Is there a way to qualify identical field names? What are some standard practices for dealing with this?
The record system is somewhat wartish, and there have been several proposals to remedy it. I'm not sure if any consensus has emerged yet. -k