43 lines
992 B
OCaml
43 lines
992 B
OCaml
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(* use with [cvs update -r objvariants typing] *)
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let f (x : [> ]) = x#m 3;;
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let o = object method m x = x+2 end;;
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f (`A o);;
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let l = [`A o; `B(object method m x = x -2 method y = 3 end)];;
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List.map f l;;
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let g = function `A x -> x#m 3 | `B x -> x#y;;
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List.map g l;;
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fun x -> ignore (x=f); List.map x l;;
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fun (x : [< `A of _ | `B of _] -> int) -> ignore (x=f); List.map x l;;
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class cvar name =
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object
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method name = name
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method print ppf = Format.pp_print_string ppf name
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end
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type var = [`Var of cvar]
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class cint n =
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object
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method n = n
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method print ppf = Format.pp_print_int ppf n
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end
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class ['a] cadd (e1 : 'a) (e2 : 'a) =
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object
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constraint 'a = [> ]
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method e1 = e1
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method e2 = e2
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method print ppf = Format.fprintf ppf "(%t, %t)" e1#print e2#print
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end
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type 'a expr = [var | `Int of cint | `Add of 'a cadd]
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type expr1 = expr1 expr
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let print = Format.printf "%t@."
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let e1 : expr1 = `Add (new cadd (`Var (new cvar "x")) (`Int (new cint 2)))
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