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Same label in different types, how do people solve this?
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Date: | 2000-12-08 (09:24) |
From: | Sven LUTHER <luther@d...> |
Subject: | Re: Same label in different types, how do people solve this? |
On Fri, Dec 08, 2000 at 10:22:29AM +0900, Jacques Garrigue wrote: > From: "Mattias Waldau" <mattias.waldau@abc.se> > > > In Ocaml, you cannot have the same label in different types, see the example > > below where > > point_2d hides point_3d. > > > > How do people normally code around this restriction? One solution is using > > objects, but what other solutions are there? Can 'Polymorphic variants' > > solve this? > > There are various ways. The most common is to differentiate label > names (i.e. use x_3d and x_2d instead of x). Another more subtle one > is to put the definitions in deifferent modules (Point2d and Point3d) > so that you can specify exactly which label you want (Point2d.x or > Point3d.x). > > The last solution might be nicer if we had a > let open Module in > construct (would require 10 lines in the compiler) Is this not already possible ? i read about something similar in the docs somewhere ... Another idea would be to add some construct to use something like : type p3d = { x:float;y:float;z:float } type p2d = { x:float;y:float } and then be able to do : {p3d.x=10.;p3d.y=20.;p3d.z=30.} and {p2d.x=0; p2d.y=5} Would this be difficult to do ? Friendly, Sven Luther