What I don't like about current accessory functions is that they pollute
namespace.
data Coordinate2D = Coordinate2D { x :: Double, y :: Double}
will make x and y not available for other types:
data Coordinate3D = Coordinate3D { x :: Double, y :: Double, z :: Double}
What I am proposing is something like this:
data Coordinate = Coordinate where { x :: Double, y :: Double}
By using "where" (or other keyword) we mark those accesor functions as local to
type. This means, that function can only be used in a context of a type, like
this:
coord <- getRandomCoordinate
For modifying (same as current):
let newCoord = coord {x = 3, y = 4}
For accessing part of a type:
let x = coord.x
Current form "x coord" will generate error, as there is no standalone function
"x". "x" can only be accessed in context of any function application that
returns needed type. Meaning, it is valid to write something like this:
let plus (Coordinate2D x1 y1) (Coordinate2D x2 y2) = Coordinate2D (x1+x2)
(y1+y2)
x = (plus coord coord).x
Yes, that means that function composition will need to use another symbol, but
I think it is a great trade-off, as it will reduce namespace pollution and will
make use of notation familiar to mainstram programmers (Java, C#, C, C++, etc).
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